Sextus replies to the charge that the Sceptics deny phenomena by refuting it.[1] The Sceptic does not deny phenomena, because they are the only criteria by which he can regulate his actions. "We call the criterion of the Sceptical School the phenomenon, meaning by this name the idea of it."[2] Phenomena are the only things which the Sceptic does not deny, and he guides his life by them. They are, however, subjective. Sextus distinctly affirms that sensations are the phenomena,[3] and that they lie in susceptibility and voluntary feeling, and that they constitute the appearances of objects.[4] We see from this that Sextus makes the only reality to consist in subjective experience, but he does not follow this to its logical conclusion, and doubt the existence of anything outside of mind. He rather takes for granted that there is a something unknown outside, about which the Sceptic can make no assertions. Phenomena are the criteria according to which the Sceptic orders his daily life, as he cannot be entirely inactive, and they affect life in four different ways. They constitute the guidance of nature, the impulse of feeling; they give rise to the traditions of customs and laws, and make the teaching of the arts important.[5] According to the tradition of laws and customs, piety is a good in daily life, but it is not in itself an abstract good. The Sceptic of Sextus' time also inculcated the teaching of the arts, as indeed must be the case with professing physicians, as most of the leading Sceptics were. Sextus says, "We are not without energy in the arts which we undertake."[6] This was a positive tendency which no philosophy, however negative, could escape, and the Sceptic tried to avoid inconsistency in this respect, by separating his philosophy from his theory of life. His philosophy controlled his opinions, and his life was governed by phenomena. [1] _Hyp._ I. 19. [2] _Hyp._ I. 19. [3] _Hyp._ I. 22; Diog. IX. 11, 105. [4] _Hyp._ I. 22. [5] _Hyp._ I. 23. [6] _Hyp._ I. 24.