Socrates says “know thyself”: I say which self?

[Ben Masada]

Interestingly, the way Plato/Socrates used the phrase "Know Thy Self" simply meant 'know your place, do not become bigger than your britches'.

Could someone of the size of Plato/Socrates' mind have such a picture of one self in a society of slaves? To know one's place as not bigger than one's britches (breeches) would be of slaves and not of masters.
Ben