Whether the universe is a concourse of atoms, or nature is a system, let this first be established, that I am a part of the whole which is governed by nature; next, I am in a manner intimately related to the parts which are of the same kind with myself. For remembering this, inasmuch as I am a part, I shall be discontented with none of the things which are assigned to me out of the whole; for nothing is injurious to the part, if it is for the advantage of the whole. For the whole contains nothing which is not for its advantage; and all natures indeed have this common principle, but the nature of the universe has this principle besides, that it cannot be compelled even by any external cause to generate anything harmful to itself. By remembering, then, that I am a part of such a whole, I shall be content with everything that happens. And inasmuch as I am in a manner intimately related to the parts which are of the same kind with myself, I shall do nothing unsocial, but I shall rather direct myself to the things which are of the same kind with myself, and I shall turn an my efforts to the common interest, and divert them from the contrary. Now, if these things are done so, life must flow on happily, just as thou mayest observe that the life of a citizen is happy, who continues a course of action which is advantageous to his fellow-citizens, and is content with whatever the state may assign to him.
The parts of the whole, everything, I mean, which is naturally comprehended in the universe, must of necessity perish; but let this be understood in this sense, that they must undergo change. But if this is naturally both an evil and a necessity for the parts, the whole would not continue to exist in a good condition, the parts being subject to change and constituted so as to perish in various ways. For whether did nature herself design to do evil to the things which are parts of herself, and to make them subject to evil and of necessity fall into evil, or have such results happened without her knowing it? Both these suppositions, indeed, are incredible.