Three Fields of Study
Stoicism included three main areas of study:
- Logic (modern logic, proper, rhetoric, epistemology and cognitive science)
- Physics (modern natural science, metaphysics and theology)
- Ethics (the study of how live your best life)
In “Lives of the Eminent Philosophers” a rich anecdotal introduction to the major and minor figures of ancient Greek Philosophy, Diogenes Laertius references the three parts:
“I have decided to give a general account of all the Stoic doctrines in the life of Zeno because he was the founder of the School. I have already given a list of his numerous writings, in which he has spoken as has no other of the Stoics. And his tenets in general are as follows.” (DL, VII.38)
“Philosophic doctrine, say the Stoics, falls into three parts: one physical, another ethical, and the third logical. Zeno of Citium was the first to make this division in his Exposition of Doctrine.” (DL, VII.39)
“Philosophy, they say, is like an animal, Logic corresponding to the bones and sinews, Ethics to the fleshy parts, Physics to the soul. Another simile they use is that of an egg : the shell is Logic, next comes the white, Ethics, and the yolk in the centre is Physics. Or, again, they liken Philosophy to a fertile field : Logic being the encircling fence, Ethics the crop, Physics the soil or the trees. Or, again, to a city strongly walled and governed by reason.
No single part, some Stoics declare, is independent of any other part, but all blend together. Nor was it usual to teach them separately. Others, however, start their course with Logic, go on to Physics, and finish with Ethics ; and among those who so do are Zeno in his treatise On Exposition, Chrysippus, Archedemus and Eudromus.” (DL, VII.40)