Book 9
11.81
The third mode depends on the differences between the sense-channels in different cases, for an apple gives the impression of being pale yellow in colour to the sight, sweet in taste and fragrant in smell. An object of the same shape is made to appear different by differences in the mirrors reflecting it. Thus it follows that what appears is no more such and such a thing than something different.
11.82
The fourth mode is that due to differences of condition and to changes in general; for instance, health, illness, sleep, waking, joy, sorrow, youth, old age, courage, fear, want, fullness, hate, love, heat, cold, to say nothing of breathing freely and having the passages obstructed. The impressions received thus appear to vary according to the nature of the conditions. Nay, even the state of madmen is not contrary to nature; for why should their state be so more than ours? Even to our view the sun has the appearance of standing still. And Theon of Tithorea used to go to bed and walk in his sleep, while Pericles’ slave did the same on the housetop.
