“Do not then suppose that these words are rashly spoken by us, O Protarchus, for they are in harmony with the testimony of those who said of old time that mind rules the universe.”
Socrates invokes earlier thinkers in a discussion of whether intelligence helps order the cosmos. The claim concerns an ancient metaphysical account of mind as a cause, not the modern sense of an individual person’s mental health or an experimentally settled account of the universe.
Source details
Plato, Philebus, approximately 30c–d; Socrates addressing Protarchus amid the argument that reason or mind belongs with the ordering cause rather than with limitless pleasure. Benjamin Jowett English, Project Gutenberg #1744, dialogue text.