A noir, E blanc, I rouge, U vert, O bleu: voyelles. Baudelaire, Le sonnet des voyelles Toute personne percevant une couleur eprouve la meme sensation et apprehende la meme qualite de vecu. C'est pourquoi la sensation que provoque la couleur est un langage sensible comprehensible partous sans recours au vocabulaire: un langage visuel. Luscher, 'Les couleurs sont des sentiments visualises'Synesthesia is, in rough terms, the spillover from one sense modality into another. An intense experience in one sense modality, sight for example, can lead to an accompanying sensation in another modality, such as hearing. Synesthesia is simultaneously one of the most simple and the most complex articulations of signs. The simplest in that the signifier and the signified are the same, just shifted by a sense modality. The most complex in that the signifier and the signified are simultaneous. That is, we speak of a sound 'evoking' a certain color, the sound becomes a sign for that color, but actually the sound and the color occur simultaneously -the sound and the color are part of the same sensory experience. We immediately interpret our sensations, pushing apart the two sensory experiences temporally, to allow one to signify the other. We see the human need to filter experience by a system of signification, to map sensation onto a logical grid. In a certain sense most signs are synesthetic -for example, the sound of a word is a sign for a visual concept, the sound of the spoken sound 'bird' is a sign for the image of the bird flying above. Although separated by the sensory modalities of hearing and sight, the two concepts 'meet in the brain' so to speak. This dual nature of Synesthesia -at once simple and complex -is reflected in our associations of the synesthetic Semiotica 58-1/2 (1986), 107-121.