I am not sure that the web weaved by Persephone in this Orphic tale, cited in exergue of Michel Serres’ La communication  , is what we are currently used to call the World Wide Web. Our computer web on the internet is nevertheless akin Persephone’s in its aims : representing and covering the entire universe. Our learned ignorance is conceiving an infinite virtual world whose center is everywhere and circumference nowhere ...
We will try in this paper to develop a semiotic analysis of computer-based communication, and especially human-to-human communication through an electronic medium. Semiotics is a very interesting and powerful tool in order to rephrase information theory and computer science and shed a new light on this global phenomenon. Along with semiotics, we will nevertheless also base our study on a more classical historical analysis, sometimes verging on historicism, to point out the deep roots of contemporary computer communication. We will therefore retrace the history of the ‘universal language of computer’, that is, binary notation, and link it to that of the ‘universal language of images’, that is, a long tradition in the history of ideas going back to Cicero’s Art of Memory and various Renaissance curiosities.
Computers are artefacts aimed at storing and manipulating information -- information being basically anything that could be algorithmically generated -- encoded in various ways. Information theory can be thought of as some sort of simplified or idealized semiotics : a cyphering/decyphering algorithm represents the interpretation process used to decode some signifier (encoded information) into some computable signified (meaningful information) to be fed to a subsequent processing step. As could be this process, semiosis is, of course, unlimited.
Communication between computers follows the same scheme. As data have
to be transmitted through some external (usually analog) medium, a further
encryption scheme (semiotic system) has to be devised and applied : the
communication protocol. The current success of the World Wide Web protocol
on the internet (http) is mainly due to its ability to manipulate images
and sound in addition to simple alphanumeric text. As humans communicate
through this medium and exchange cultural signs, some problematic issues
should be raised. Indeed, the human being has to decompose himself as a
collection of transmissible and immediatly understandable signs in order
to be communicable, and this drift can be seen today in personal Web pages
or electronic mail communications. The self is mutilated and disintegrated
into conventional signs, in a deeper and much more dramatic way than oral
communication. The success of the Web goes with its semantic poverty, and
is heading toward some "zero degree" of communication. The Entropy Principle
warns us that we are converging towards a stable state where everyone will
be connected and fully informed of a homogeneous and therefore null content.
II. The Universal Language of Machines
The success of the computer as a universal information-processing machine
lies essentially in the fact that there exists a universal language in
which many different kinds of information can be encoded and that this
language can be mechanized. This would concretize the well-known dream
of Leibniz of a universal language that would be both a lingua characteristica,
allowing the ‘’perfect’’ description of knowledge by exhibiting the ‘’real
characters’’ of concepts and things, and a calculus ratiocinator, making
it possible for the mechanization of reasoning. If such a language was
employed, Leibniz said, errors in reasoning would be avoided, and endless
philosophical discussions would cease at once by having all philosophers
sit aroung a table and say ‘’calculemus’’. This would indeed reify Thomas
Hobbes motto : ‘’cogitatio est computatio’’.
Surprisingly enough - or maybe not - Leibniz is also commonly credited with the invention of the universal language of computers : binary notation (see Fig. 1). It seems however that the binary notation was originally used circa 1600 by Thomas Harriot , the English astronomer, famous for speaking about the " strange spotednesse of the moon " and being unable to associate it with the mountains and seas of the planet. A few months later, Galileo was the first to actually ‘’see’’ the relief of the moon, in all likelihood because of his training in fine arts (geometry of shadow casting and chiarioscuro), making this event a landmark in the mutual influence of Art and Science  . Back to binary notation, Leibniz himself found a predecessor in Abdallah Beidhawy, an Arab scholar of the thirteenth century. A few other authors also proposed binary notations during the seventeenth century, but it was not until its ‘’discovery’’ and publication by Leibniz in 1703  that it started a growing interest in non-decimal numerical systems. Leibniz’s invention can be traced back to 1697, in a letter to the Duke of Brunswick detailing the design of a medallion (see figure), but he delayed its publication until finding an interesting application. The one he choose was the explanation of the Fu-Hi figures, the hexagrams of the I-Ching, or book of changes, from ancient China, that have been communicated to him in 1700 by the Father Bouvet, a jesuit missionary in China. Two centuries and a half later, binary notation found another application with a much broader impact : digital computers  . Altrough the first computer, the ENIAC machine created in 1946, made use of a notation that was a sort of hybrid between decimal and binary, the application of full binary notation was generalized in the following years, after the Burk-Goldstine-Von Neuman Report of 1947 :
" An additional point that deserves emphasis is this : An important part of the machine is not arithmetical, but logical in nature. Now logics, being a yes-no system, is fundamentally binary. Therefore, a binary arrangement of the arithmetical organs contributes very significantly towards a more homogeneous machine, which can be better integrated and is more efficient " .
This report indeed defined the so-called IAS computer design, which formed the basis of most of the systems from the early fifties, that were indeed the first purely binary machines : IBM 701 1952, ILLIAC, University of Illinois 1952, MANIAC, Los Alamos Scientific Laboratory 1952, AVIDAC, Argonne National Laboratory 1953, BESK, Sweden 1953, BESM, Moscow 1955, WEIZAC, Israel 1955, DASK, Danemark 1957, etc  .
Computers can compute, for sure, and using binary notation for representing numbers is certainly of great interest, but there is nevertheless another key issue for making them able to process higher-level information. The first step was to code alphabetical symbols, therefore moving from the realms of numbers to the realms of words. The first binary encoding of alphanumeric characters was indeed designed a century ago in 1898 by Giuseppe Peano, the very Peano responsible for the first axiomatization of arithmetics  . He designed an abstract stenographic machine based on a binary encoding of all the syllables of the Italian language. Along with the phonemes, coded with 16 bits (allowing therefore 65 536 combinations), there was an encoding of the 25 letters of the (Italian) alphabet and the 10 digits. Peano's code, perhaps too technologically advanced for its time or simply too exotic, passed unnoticed and has been long forgotten. Nowadays, computers employ the ASCII encoding of letters and numbers that represent each character with 7 bits (or 8 for extended ASCII, which includes accentuated letters). Being able to handle numbers and letters, the computer soon became the perfect data-processing machine, the flawless artifact of the information technology age.
Another landmark, however, is crucial: the digitalization and, of course,
binarization of pictures, which marked the opening of the realms of images
to the computer. This technology was, to the best of my knowledge, first
revealed to the general public in the mid 60's, during the heyday of space
exploration. Time magazine, relating the Mariner IV mission to Mars (whose
TV camera transmitted back the first pictures ever of the surface of the
red planet) wrote : 
" Each picture was made up of 200 lines – compared with 525 lines of commercial TV screens. And each line was made up of 200 dots. The pictures were held on the tube for 25 seconds while they were scanned by an electron beam that responded to the light intensity of each dot. This was translated into numerical code with shadings running from zero for white to 63 for deepest black. The dot numbers were recorded in binary code of ones and zeros, the language of computers. Thus white (0) was 000000, black (63) showed up as 111111. Each picture – actually 40,000 tiny dots encoded in 240,000 bits of binary code – was stored on magnetic tape for transmission to the Earth after Mariner had passed Mars. More complex in some respects than the direct transmission of video data that brought pictures back from the moon, the computer code was necessary to get information accurately all the way back from Mars to Earth. "
As a matter of comparision, modern computers might handle images composed of millions of pixels (‘’small dots’’) with millions of colors, requiring about 100 times more bits of binary codes.
Indeed, this ability to manipulate pictorial information proved to be the main reason for the current explosion of cyberspace and the internet. Without images, with human-to-computer and human-to-human (through computer) interactions limited to the alphanumeric set, electronic communication was circumscribed to computer professionals and a few crucial business/military applications. Do not forget that the ancestor of the Internet was the military-funded Arpanet... The widening of the network to mainstream society, with the exponential growth and mediatization of the World Wide Web, could only emerge if electronically exchanged signs could be at the same time both more complex, to hold more information more concisely, and less dry, in order to be more pleasing aesthetically. Let us now rewind history a little and look back to the tradition of using pictorial knowledge in science and philosophy.
III. The Power of Images
The use of images to represent knowledge and synthetize information
has a long background in the Western history of ideas, particularly in
the antique tradition of the Art of Memory, a strand of classical studies
going back to Cicero and persisting until the late Renaissance  . This
discipline was concerned with mnemonics and the ability to memorize anything
at will, at a time when paper and other writting-supports were rare and
rhetoric a key discipline. Leibniz himself, definitively the filium Ariadne
of our study, considered that scholarship or " perfect knowledge of the
principle of all sciences and the art of applying them " could be divided
into three equally important parts : the art of reasoning (logic), the
art of inventing (combinatorics) and the art of memory (mnemonics). He
even wrote an unpublished manuscript on the ars memoriae. The main idea
of the ars memorativa is to organize one’s memory in ‘’places’’ organized
into an imaginary architecture, e. g. the rooms of a house. This basic
architecture must be well-known and familiar, in order to let oneself wander
easily within it. Then, to remember particular sequences of things, one
will populate these rooms with ‘’images’’ that should refer directly or
indirectly to what has to be remembered. The main assumption here, the
roots of which goes back obviously to Plato  , is that (visual) images
are easier to remember than words. With its emphasis on the power of images,
this tradition naturally lead to the notion of a perfect language based
on images instead of words, as images ‘’speak more directly to the soul’’.
This is in particular the case for its last incarnations such as in the
"philosopher of the infinite" Giordano Bruno, burned for heresy by the
Inquisition in 1600, or even G.W. Leibniz in the seventeenth century. Interestingly,
this Platonic consideration of immediateness of pictures (as abstractions
of ideas) has persisted up to our times, as shown by Saussure’s immediate
use of the drawing of a tree to illustrate the signified of the word ‘tree’
in the well-known Cours de linguistique générale, written
less than a century ago…
Another major figure in the Renaissance is the philosopher, utopist and ex-Domenican monk Tomasso Campanella, a contemporary of Giordano Bruno with similar -- if less definitive -- problems with the Inquisition (he visited more than 50 prisons and spent 7 years in jail before finding asylum in France). He imagined in his famous book The City of the Sun (1613) a utopian ideal city enclosed by six concentric walls painted with images that would constitute an encyclopedia of all sciences, to be learned ‘’very easily’’ by children as of age 10.
A few decades later, the Czech humanist Comenius (Jan Amos Komensky) implemented this dream in his Orbis sensualium pictus quadrilinguis (1658), " the painting and nomenclature of all the main things in the world and the main actions in life ", actually a pictorial dictionnary. Images are "the icons of all visible things in the world, to which, by appropriate means one could also reduce invisible things ". The philosophical alphabet of his global encyclopedia is an alphabet of images, as depicted in Fig. 2. A very interesting device put to use by Comenius is to attach letters or numbers to parts of the image and to refer to those symbols in the text. He therefore had recourse to indexical signs to make the image work as a global pictorial diagram. At the same time, the Jesuit father Athanasius Kircher was using the same indexical device in his famous Oedipus Aegyptiacus (1652-4) and several others of his numerous writings, such as ars magna luce et umbris (1646), exemplified in Fig. 3.
However, this utilisation of labels (letters or numbers) to decompose
a picture and reference to a more detailed explanation could yet be traced
back more than one century before. Following the paradigm shift from purely
theoritical knowledge to a more applied and engineering-oriented
vision of science in the early sixteenth century , the production
of illustrated printed books rapidly developed after 1520. As stated by
G. Sarton  , " the illustrations were not simply valuable in themselves;
their existence close to the text must eventually lead to the correction
of the latter. It became more and more objectionable to reproduce stereotyped
words in the vicinity of correct images ".
An important part of such publications was technical books on various subjects such as architecture, metallurgy, hydraulics, mechanics, anatomy, etc, with large pictures labeled in a pedagogical and diagrammatic manner. We could mention in particular Cesare Cesariano’s edition (1521) of the classical Ten Books on Architecture by Vitruvius (but not the earlier edition printed in Venice in 1497), Vesalius's De humani corpus fabrica (1543) where labels are used to name muscles, bones or various parts of the body  , Agricola's De re metallica (1556), see Fig. 3, and Ramelli's Diverse et artificiose macchine (1588) or other ‘’theaters of machines’’ describing various artifacts with, in addition to the now classical drawing conventions built up by the engineers of the Renaissance, this ingenious device of naming parts and detailling them aside. The earliest example of this device that I found comes from Ars Memorandi, a book printed in 1502 by in Pforzheim , consisting of a latin text by Peter von Rosenheim (Roseum memoriale, an aid for the study of the bible written in 1420/30) and amazing woodcuts representing memory images. For example in the "first image of John", shown in Fig. 6 and 7, the triple head labeled by 1 refers to the number 1 (Primu) in the text, that is to the trinity, etc.
At the end of the sixteenth century, this indexed split view technique was used by the Jesuits in various ways  , for instance in the frescoes of martyrdom executed by Niccolò Circigani in the Jesuit of San Stefano Rotondo in Rome (1583), or by Antonio Tempesta in his woodcuts for the trattato de gli instrumenti di martiro published in Roma in 1591 by the jesuit father Antonio Gallonio, depicting also various kinds of martyrdom. More importantly, this technique was put to use in Jerome Nadal’s Evangelicae historiae imagines (1593), a book for meditation and prayer consisting of 123 illustrations with " letters of the alphabet placed throughout the scene correspond[ing] to lettered captions of explanation underneath "  . This text was heavily used by the Jesuit missionaries in China, and Chinese copies of this book have been made, with illustrations copied by local artists  . It seems that for the Jesuits, pictures have been considered the best ‘’universal language’’ and Nadal’s famous book seems indeed to have merged the medieval tradition of illustrated meditation book, such as Pseudo-Bonaventura’s meditationes vitae Christi (late forteenth century)  , with the drawing conventions of Renaissance illustrations in technical books. Nearly identical to that of Comenius, the indexical device used in Nadal's book indeed corresponds to a primitive form of the indexical system that can be found today in the WWW...
This multiplication, not to say proliferation, of labeled images and
indexical symbols comes from a quest for pictorial realism and a descriptive
vision of the world. It is therefore interesting to distinguish, as pointed
out by Sveltana Alpers  , between the descriptive and the narrative
traditions in visual arts, exemplified by Dutch seventeenth century paintings
for the former versus Renaissance Italy for the latter. There are indeed
two different strands in our indexical device paradigm. First, the descriptive
aspect of Vesalius, Agricola, Kircher, Ramelli, etc, where labels are used
in a technical way to abbreviate on the picture the full information provided
by the text. Second, the narrative aspect of Comenius and Nadal, coming
from the Art of Memory, where labels act as hypertextual links to point
to different parts of the story. In order to properly function, this device
must follow some specific rules that persisted from the early treaties
on the Art of Memory up to Comenius  :
" We will now speak of the mode in which objects must be presented to the senses, if the impression is to be distinct. This can be readily understood if we consider the process of actual vision. If the object is to be clearly seen it is necessary : (1) that is be placed before the eyes; (2) not far off, but at a reasonable distance; (3) not on one side, but straight before the eyes; (4) and so that the front of the object be not turned away from, but directed towards, the observer; (5) that the eyes first take the object as a whole; (6) and then proceed to distinguish the parts; (7) inpecting these in order from the beginning to the end; (8) that attention be paied to each and every part; (9) until they are all grasps by means of their essential attributes. If these requisites be properly observed, vision takes place successfully; but if one is neglected its success is only partial. ".
Such words could indeed come from a manual for designing Web pages, as of today …
IV. A Web of Icons, Indexes and Symbols
It is therefore not surprizing that when computers came to the realm of images, a new dimension was added to Cyberspace (literaly indeed, from 1D to 2D) and then the term ‘’Virtual Reality’’ started to be more than a daydream. We cannot investigate here the arguably profound impact of computers on image creation through computer graphics and virtual images. Rather, we will limit our study to the integration of pictures in electronic communication. Electronic mail, i.e. alphanumeric person-to-person communication on the internet and ‘’newsgroups’’, i.e. electronic dazibaos organized by fields of interest, are rather old stories and would never have started the current media trend for the internet and the cyber-everything by themselves only. The World Wide Web did so a couple of years ago, triggering some unconscious appeal for an electronic global world of pictures and images. Web pages are attractive and full of meaningful information - or so they seem. Surfing on the Web is worth the hours spent waiting in front of the computer while data is transmitted from the other side of the planet, or spent wandering through useless information on uninteresting subjects. Our purpose here will only be to use semiotics to analyse the Web as a communication tool and determine what classical concepts are reified in it.
Let us go back to Pierce’s classical classification of signs as Icons,
Indexes and Symbols, which is very useful in understanding the different
ways in which signs operate and semiosis is performed. Let us take Arthur
Burk’s presentation of this trichotomy :
" We can best do this in term of the following examples : (1) the word ‘red’, as used in the English sentence, ‘the book is red’ ; (2) an act of pointing, used to call attention to some particular object, e.g. a tree ; (3) a scale drawing, used to communicate to a machinist the structure of a piece of machinery . All these are signs in the general sense in which the term is used by Pierce : each satisfies his definition of a sign as something which represents or signifies an object to some interpretant. (...) A sign represents its object to its interpretant symbolically, indexically, or iconically according to whether it does so (1) by being associated with its object by a conventional rule used by the interpretant (as in the case of ‘red’) ; (2) by being in existential relation with its object (as in the case of the act of pointing) ; or (3) by exhibiting its object (as in the case of the diagram). "
Let us now try to use those notions for analysing the main features of Web pages. Web pages are so-called hypertexts, that is, texts with some of their components (words or sentences), possibly linked to other (hyper)texts, and so on and so forth. The reader can navigate through the whole text in a non-linear manner, by activating so-called hot links or anchor points that are linking some piece of text to some other.
These links are an obvious example of indexes, with a word pointing to (refering to) its definition or to some related piece of information. The WWW merely extends the basic notions of hypertext by making it possible for one index to refer to some physically-distant location on a remote computer somewhere else on the Internet, together, of course, with the ability to link to and therefore communicate images and sound. However in order to act as an index, a sign has to be recognized as such, i.e. the index has to exhibit itself as a reference. This is done in hypertext by marking the hot links in blue ink, in order to make the reader aware that he can jump to another piece of hypertext or image, therefore using a conventional symbol in order to ‘’show’’ the index as such.
Web pages are usually full of small images that act as user-friendly and aesthetically appealing ways of navigating through the network. These are symbolic signs, in the sense that their object must be conventionally established in order to help the reader to orient himself in a homogeneous and unlimited cyberspace. In general, all pages at one Web site (physical/logical place hosted by some institution) are homogenized in order to use the same symbols to designate basic moves in the hypertext documentation (usually at the top or bottom of the pages), in such a way that the reader can quickly learn their conventional meaning. This can be seen in the example of the Sony Virtual Society home page, depicted in Fig. 8. In this example images act as tautologies and duplicate the textual links below, which actually give their meaning to the pictures.
It could be interesting to relate the symbols used by the designers of Sony's page to some very old pictures from Johannes Rombech's book on the Art of Memory, see Fig. 9, where one could find an image aimed at defining the optimal size of the locus to be used for a memory image : not too big and not too small, roughly a square of human size . Is it also the meta-discourse behind Sony's electronic navigation symbols ?
However, as it can be seen in many sites on the Web nowdays, symbols for hypertext links tend to become icons, as if it was their only means to get rid of the textual tautology. The final example of E-Play’s home page, an Italian fashion company, is a good instance of a fully iconic Web page. No text duplicates the iconic links, which indeed ‘’talk’’ by themselves, that is, ‘’exhibit their objects’’. After careful reading and a bit of thinking, one could indeed identify links to a male fashion gallery, a female fashion gallery, a list of shops stocking the products, etc.
A closely related shift from symbolic signs to iconic signs can also
be observed in electronic mail communication with the use of so-called
emoticons or ‘’smiley’’ signs, such as those depicted in the figure below.
These signs can be considered as conventional symbols from the cyber-jargon
that are used within an alphanumeric text to express, in a very rudimentary
manner, some personal emotions or personal facts. But they indeed become
icons if the text is turned 90o... The range of feelings that could be
expressed is rather limited and this points out in a rather crude manner
the poverty and standardization of the virtual communication towards which
we are concretely going.
However pure iconography is not possible, as icons have to present themselves as such, to display their own icon-ness. A sign is not iconic until the interpreter recognizes it as such. To that purpose the shape of the mouse pointer (the device used to move on the computer screen through the displayed text) changes when passing upon such a link, and it becomes ... a small hand with a pointed index. Thus, an index is used to identify an icon as such. But note also that an icon (pointed finger) is then used to identify the index as such. As is well-known, pure iconicity is not possible.
As in all semiotic systems, we have seen that the web is a mesh of icons,
indexes and symbols, with each type of the trichotomy indeed depending
on the others, even for its own definition. Althrough the web in its essence
and its success relies heavily on images, the dream of a 'perfect language
of images' cannot be reified with this medium either. Pure iconicity is
always fading away in the distance...
We cannot here resist to put this problem in parallel with W. V. Quine’s famous counter-example showing the impossibility of learning a language from scratch. Imagine yourself as an adventurous linguist marooned in some unknown territory hosted by a primitive tribe (to give an exotic thrill). You are trying to learn their language, and at some point your host points his index towards a rabbit running in the distance and says ‘’gavagai’’. What could you deduce from that ? That ‘’gavagai’’ means rabbit ? Or ‘’in the distance’’ ? Or ‘’brown-grey’’ ? Or ‘’this is our meal for tonight’’ ? Or that this rabbit is called ‘’gavagai’’ ? Or that it means ‘’Go home !’’ ? If the indexical sign is not clearly identified, (and how could it be identified ?), this iconic way of learning a language (word meanings by analogy with existing things) cannot work. Observe nevertheless that we have yet a fairly strange semiotic system ‘’in reverse’’ where the linguistic signs are the signified and the ‘’real’’ things are the signifiers, in so far as things could be real, are the signifiers ...
1) Michel Serres, Hermes I : La communication, éditions de minuit, Paris, 1968.
2) See A. Glaser, History of Binary and other nondecimal Numeration, Tomash Publishers, Philadelphia, USA, 1981.
3) Galileo, Sidereus Nuncius, Venice, 1610.
See for instance Samuel Y. Edgerton, Jr., The Heritage of Giotto’s Geometry, Art and Science on the Eve of the Scientific Revolution, Cornell University Press, Ithaca, USA, 1991, chapter 7.
4) ‘’Explication de l’arithmétique binaire’’, Mémoires de l’Académie Royale des Sciences, Paris, 1703.
5) For a basic history of early computing, see P. Levy, "l'invention de l'ordinateur", in M. Serres (Ed.), Eléments d'histoire des sciences, Bordas, Paris, 1993, or W. Aspray, John Von Neumann and the origins of Modern Computing, The MIT Press, Cambridge, USA, 1990.
6) A. W. Burks, H. H. Goldstine and J. von Neumann, Preliminary Discussion of the Logical Design of an Electronic Computing Instrument, Institute for Advanced Studies, Princeton, USA, 1947.
7) Cf. W. Aspray, op. cit.
8) G. Peano, "La numerazione binaria applicata alle stenographia", in opere scelte vol. III, Edizione Cremonese, Roma, 1959. Also cited in A. Glaser, op. cit.
9) ‘’Space Exploration’’, Time 86, July 23th, 1965.
10) The basic references on this topic are : Frances Yates, The
Art of Memory, Chicago University Press 1990 (first edition: London,
1966), and Paolo Rossi, Clavis Universalis, éditions
Millon, Grenoble, 1993 (first edition: Milan, 1960).
As a matter of fact, this tradition started back in Greece with a tale and a mythical hero. Our story would tell the glorious birth of the Art of Memory, and our hero would be the famous poet Simonides of Ceos.
11) Cf. I. P. Couliano, Eros and magic in the Renaissance, University of Chicago Press, 1987
12) On this "paradigm shift", see for instance P. Rossi, Philosophy, Technology, and the Arts in the Early Modern Era, Harper and Row, New York, 1970, and H. Bredekamp, The Lure of Antiquity and the Cult of the Machine, Markus Wiener, Princeton, 1995.
13) G. Sarton, The Appreciation of Ancient and Medical Science
during the Renaissance, Philadelphie, 1955, cited in P. Rossi, op. cit.
14) Cf. M. Kemp, "Temples of the Body and Temples of the Cosmos : Vision and Visualization in the Vesalian and Copernican revolutions", in B. S. Baigrie (Ed.), Picturing Knowledge, University of Toronto Press, 1996.
15) Amodern reprint has been published by the Houghton Library, Harvard University, 1981.
16) Thomas Buser ‘’Jerome Nadal and Early Jesuit Art in Rome’’, Art Bulletin, 57 (1976) : 424-433.
17) Thomas Buser, op. cit.
18) See S. Y. Edgerton, op. cit, chapter 8.
19) See I. Ragusa and R. Green (Eds.), Meditations on the
Life of Christ, Princeton, 1961.
I am indebted to Karin Boklund, from the University of Thessaloniki, Greece, for this historical connection.
20) S. Alpers, The Art of Describing, University of Chicago Press, 1983.
21) Comenius, The Great Didactics, Russel and Russel, New York, 1967, originally published in latin in 1641, cited in S. Alpers, op. cit.
22) Arthur W. Burks, ‘’ Icon, Indexes and Symbols ‘’, Philosophy and Phenomenological Research, vol. 9 n. 4, June 1949.
23) This convention in Medieval and Renaissance treatises
on the ars memorandi have led some scholars such as Frances Yates, op.
cit., to consider Giotto's allegories in the Arena Chapel in Padua as designed
along the same rules.