Ralph Waldo Emerson's poem entitled 'Know Thyself', which he treated his own anthem, the aphorism stands for knowing the God, which exists within each person.
In ancient India, the techniques like meditation, self-observation, introspection, self-knowledge, Jnana-Bhakati-Karma Yoga, etc., were used for knowing one's true self or eternal soul that embodies all.
It has been wisely said by Lao Tzu, "He who knows others is wise; he who knows himself is enlightened.” In the similar vein Doris Mortman once said, “Until you make peace with who you are, you'll never be content with what you have.”
Here are my three haiku on knowing oneself.
Release is action
It's action through inaction?
It just happens.?
Know thyself - pure you?
Work on yourself to get pure?
Be your own witness.?
Witnessing your true being?