(3) The art of the BEAUTIFUL PLAY OF SENSATIONS (externally stimulated), which admits at the same time of universal communication, can be concerned with nothing else than the proportion of the different degrees of the disposition (tension) of the sense, to which the sensation belongs, _i.e._ with its tone. In this far-reaching signification of the word it may be divided into the artistic play of the sensations of hearing and sight, _i.e._ into _Music_ and the _Art of colour_.--It is noteworthy that these two senses, besides their susceptibility for impressions so far as these are needed to gain concepts of external objects, are also capable of a peculiar sensation bound up therewith, of which we cannot strictly decide whether it is based on sense or reflection. This susceptibility may sometimes be wanting, although in other respects the sense, as regards its use for the cognition of Objects, is not at all deficient but is peculiarly fine. That is, we cannot say with certainty whether colours or tones (sounds) are merely pleasant sensations or whether they form in themselves a beautiful play of sensations, and as such bring with them in aesthetical judgement a satisfaction in their form. If we think of the velocity of the vibrations of light, or in the second case of the air, which probably far surpasses all our faculty of judging immediately in perception the time interval between them, we must believe that it is only the _effect_ of these vibrations upon the elastic parts of our body that is felt, but that the _time interval_ between them is not remarked or brought into judgement; and thus that only pleasantness and not beauty of composition is bound up with colours and tones. But on the other hand, _first_, we think of the mathematical [element] which enables us to pronounce on the proportion between these oscillations in music and thus to judge of them; and by analogy with which we easily may judge of the distinctions between colours. _Secondly_, we recall instances (although they are rare) of men who with the best sight in the world cannot distinguish colours, and with the sharpest hearing cannot distinguish tones; whilst for those who can do this the perception of an altered quality (not merely of the degree of sensation) in the different intensities in the scale of colours and tones is definite; and further, the very number of these is fixed by _intelligible_ differences. Thus we may be compelled to see that both kinds of sensations are to be regarded not as mere sensible impressions, but as the effects of a judgement passed upon the form in the play of divers sensations. The difference in our definition, according as we adopt the one or the other opinion in judging of the grounds of Music, would be just this: either, as we have done, we must explain it as the beautiful play of sensations (of hearing), or else as a play of _pleasant_ sensations. According to the former mode