Meditation 10.6
6. Whether there are Atoms or Nature, the first postulate must be: 'I am part of the Whole which is governed by Nature'; the second: 'I am allied in some way to the parts that are of the same kind with me.' For if I remember these postulates, I shall, in so far as I am a part, not be disaffected to anything assigned by the Whole; for nothing which benefits the Whole is injurious to the part, since the Whole contains nothing which does not benefit itself, and while all natural existences have this common attribute, the nature of the Universe has this farther attribute that no external cause can compel it to generate anything injurious to itself.
By remembering, therefore, that I am a part of a Whole so characterized, I shall be well-affected to all that results from it, and in as much as I am allied in some way to the parts of the same kind as myself, I will do no unsocial act, rather I will study the good of my kind and direct every impulse to the common benefit and divert it from what opposes that benefit. Now when things are being accomplished in this way, life must needs flow smoothly, just as you would see that a citizen's life is smooth as he progresses by acts which benefit his fellow-citizens and welcomes whatever his city assigns.