Book 7
1.52
The Stoics apply the term sense or sensation (αἴσθησις) to three things: (1) the current passing from the principal part of the soul to the senses, (2) apprehension by means of the senses, (3) the apparatus of the sense-organs, in which some persons are deficient. Moreover, the activity of the sense-organs is itself also called sensation. According to them it is by sense that we apprehend black and white, rough and smooth, whereas it is by reason that we apprehend the conclusions of demonstration, for instance the existence of gods and their providence. General notions, indeed, are gained in the following ways: some by direct contact, some by resemblance, some by analogy, some by transposition, some by composition, and some by contrariety.
1.53
By incidence or direct contact have come our notions of sensible things; by resemblance notions whose origin is something before us, as the notion of Socrates which we get from his bust; while under notions derived from analogy come those which we get (1) by way of enlargement, like that of Tityos or the Cyclops, or (2) by way of diminution, like that of the Pygmy. And thus, too, the centre of the earth was originally conceived on the analogy of smaller spheres. Of notions obtained by transposition creatures with eyes on the chest would be an instance, while the centaur exemplifies those reached by composition, and death those due to contrariety. Furthermore, there are notions which imply a sort of transition to the realm of the imperceptible: such are those of space and of the meaning of terms. The notions of justice and goodness come by nature. Again, privation originates notions; for instance, that of the man without hands. Such are their tenets concerning presentation, sensation, and thought.
