Wisdom from the Early Stoics, Zeno of Citium 26

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.

—Diogenes Laërtius, 7.52