One of the perks of being a psychologist is access to tools that allow you to carry out the injunction to know thyself.

The ancient precept, “Know thyself,” and the modern precept, “Study nature,” become at last one maxim.

One has to know the size of one's stomach.

No one is free who has not obtained the empire of himself. No man is free who cannot command himself.

Know thyself? If I knew myself I would run away.

Self-awareness is not self-centeredness, and spirituality is not narcissism. 'Know thyself' is not a narcissistic pursuit.