From Pies' Everything Has Two Handles:
"'Things do not touch the soul, for they are external and remain immovable; but our perturbations come only from the opinion which is within . . . The universe is transformation, life is opinion.'
~ Marcus Aurelius (Long, 54)
'Things do not touch the soul.' This deceptively simple statement is the keystone in the arch of Stoic philosophy."
Pies has a knack for getting straight to the heart of the matter! If one were looking for a good summation of Stoic philosophy, this might be a good candidate! The first chapter is supported with other sententious maxims from Marcus Aurelius, directly or indirectly - "Change your opinions, change the way you feel!" "Whatever man you meet, say to yourself at once: 'What are the principles this man entertains about human goods and ills?' . . . then it will not seem surprising or strange . . . if he acts in certain ways . . ." "Get rid of the judgment, you are rid of the 'I am hurt'; get rid of the 'I am hurt,' you are rid of the hurt itself."
And so we get to the quote from Epictetus that gives us the title of the book:
"'Everything has two handles - one by which it may be borne, another by which it cannot. If your brother acts unjustly, do not lay hold on the affair by the handle of his injustice, for by that it cannot be borne; but rather, by the opposite: that he is your brother, that he was brought up with you; and thus, you will lay hold on it as it is to be borne.'
~ Epictetus (Bonforte, 84)"
There follows a pretty good analysis of Stoicism's common points of reference with Talmudic philosophy in Judaism, Buddhist philosophy, Hindu thought, et cetera.