“The greatest authors, and the greatest number of authors, have maintained that there are three divisions of philosophy – moral, natural, and rational”
Read: ethics, physics, and logic.
The first keeps the soul in order; the second investigates the universe; the third works out the essential meanings of words, their combinations, and the proofs which keep falsehood from creeping in and displacing truth.
I quite like the examples that we see elsewhere, of the egg, garden, and animal. It shows the interrelated nature of the parts, producing the whole.
Aristo of Chios remarked that the natural and the rational were not only superfluous, but were also contradictory
In this, I must disagree with Aristo. While I do subscribe to this heterodox Stoic position that we can rightly do away with the preferred and dispreferred indifferent things, I think this takes us a step too far. It may even put us back in the Cynic camp, or as was Aristo’s case, possibly a new school.
Since, therefore, philosophy is threefold, let us first begin to set in order the moral side. It has been agreed that this should be divided into three parts. First, we have the speculative part, which assigns to each thing its particular function and weighs the worth of each; it is highest in point of utility. For what is so indispensable as giving to everything its proper value? The second has to do with impulse, the third with actions
Here we have something looking like Epictetus’ Three Disciplines/Τόποι. I haven’t seen that elsewhere in the Stoic literature, although it’s a firmly established part of the School since Epictetus’ time. I had assumed previously that it was a novel addition by him, but we here we see strains of it elsewhere and before Epictetus’ time as well.
I look forward to the rest of the letter.