we believe to be square, sometimes appear round; that those which we fancy even, appear full of projections; those which we think straight, seem bent; and those which we believe to be colourless, appear of quite a different complexion. Accordingly, the sun, on account of its distance from us, appears small. The mountains too, at a distance,11 appear airy masses and smooth, but when beheld close, they are rough. Again, the sun has one appearance at his rise, and quite a different one at midday. And the same body looks very different in a wood from what it does on plain ground. So too, the appearance of an object changes according to its position as regards us; for instance, the neck of a dove varies as it turns. Since then, it is impossible to view these things irrespectively of place and position, it is clear that their real nature is not known.
The eighth mode has respect to the magnitudes or quantities of things; or to the heat or coldness, or to the speed or slowness, or to the paleness or variety of colour of the subject. For instance, a moderate quantity of wine when taken invigorates, but an excessive quantity weakens. And the same is the case with food, and other similar things.
The ninth depends upon the frequency, or rarity, or strangeness of the thing under consideration. For instance, earthquakes excite no wonder among those nations with whom they are of frequent occurrence; nor does the sun, because he is seen every day.
The ninth mode is called by Phavorinus, the eighth, and by Sextus and Ænesidemus, the tenth; and Sextus calls the tenth the eighth, which Phavorinus reckons the tenth as the ninth in order.
The tenth mode refers to the comparison between one thing and another; as, for instance, between what is light and what is heavy; between what is strong and what is weak; between what is greater and what is less;