Seneca · On the usefulness of basic principles
Letters 95.53
Let this verse be in your heart and on your lips:
I am a man; and nothing in man’s lot Do I deem foreign to me.
Let us possess things in common; for birth is ours in common. Our relations with one another are like a stone arch, which would collapse if the stones did not mutually support each other, and which is upheld in this very way.
Seneca, Letters to Lucilius 95.53, translated by Richard Mott Gummere