the cause is not the effect, and the effect is not the cause. "The beautiful is that which delights the sight and hearing." But this fails to persuade for three reasons: firstly, because beautiful studies and laws are beautiful, which have nothing to do with the eye or with the ear; secondly, because we cannot discover a reason for limiting the beautiful to those senses, while excluding the pleasure of eating and smelling, and the extremely vivid pleasures of sex; thirdly, because, if the foundation of the beautiful were _visibility,_ it would not be _audibility,_ and if it were audibility it would not be visibility; hence that which constitutes the beautiful cannot dwell in either of the two qualities. And the question which has been repeated so insistently in the course of the dialogue: _what is the beautiful?_ (τί εστι το καλόν;) remains unanswered.[18] Later writers also conducted inquiries into the beautiful, and we possess the titles of several treatises upon the theme, which have been lost. Aristotle shows himself changeable and uncertain upon the point. In the scanty references which he makes to it, he at one time confounds the beautiful with the good, defining it as that which is both good and pleasing;[19] at another he notes that the good consists of action (εν πράξει) and the beautiful also in things that are immoveable (εν τοΐς άκινήτοις), drawing from this the argument that mathematics should be studied in order to determine its characters, order, symmetry and limit;[20] sometimes he places it in bigness and in order (εν μεγεθει καί τάξει);[21] at others he was led to look upon it as something apparently indefinable.[22] Antiquity also established canons of beautiful things, such as that attributed to Polycletus on the proportions of the human body. And Cicero said of the beauty of bodies that they were "_quaedam apta figura membrorum cum coloris quadam suavitate._"[23] All these affirmations, even when they are not mere empirical observations, or verbal glosses and substitutions, meet with unsurmountable obstacles. [Sidenote: _Distinction between the theory of Art and the theory of the Beautiful._]