This above all: to thine ownself be true,
And it must follow, as the night the day,
Thou canst not then be false to any man. (Hamlet)
The usual reading of this is that one should avoid self-deception. This means being honest with oneself about motivation and plot.
Γνῶθι σαυτόν
Know thyself (inscribed upon the Temple of Apollo in Delphi)
This latter saying has gone through various incarnations, from the humility of recognising one's limits, through familiarity with one's own 'soul', through recognising one's origin in God and the sinfulness of self, to, per Hobbes, the notion of understanding others by understanding oneself.
Every virtue can be taken to a fault. The first saying is commonly, or in fact usually, corrupted to, 'Do what you want, or you are betraying yourself.' Equating the desired with the good and the right is obvious folly, once one stands back from the autolatry of the contemporary world. The second saying is more problematic, partly because of the latitude it allows and partly because its misuse can seem so virtuous, chiming as it does with precepts of religion, spirituality, and psychoanalysis.
In certain quarters, the notion of knowing oneself is narrowed to this: not a cool, disinterested analysis of the probity of one's beliefs, the validity of one's thinking, the utility and morality of one's behaviour, but a poetic capturing of evanescent feelings, the butterfly collector's obsession with pinning and thereby killing any elusive or unusual feeling to adorn the collector's own study, the exquisite portrayal of subjective impressions. Everyone wants to be Proust. The neophyte in this pursuit appears solipsistic, rambling, incoherent. The adept, often bolstered with professional help and practice, can captivate an audience with his wry, arch, self-deprecating acuity, his insight into the damaged mechanisms of his own mind, and it can superficially appear that what has been attained is genuine knowledge and wisdom.
The abstraction from the actual universe to one's feelings in response to it, and thence to one's thoughts about one's feelings, and thence to one's feelings about one's thoughts about one's feelings, in an infinite regress, removes the person to a rarefied plane of artistic articulacy (form without substance, grammar without sense, the raised eyebrow that was all that remained when the person himself faded, like the Cheshire Cat), whilst the person's actual life continues to deteriorate, the headless body lurching and thrashing with no one to direct its movements. The suave discourser becomes suavity itself, a property in search of an object, a definition in search of a definiendum.
I once became so lost in this pursuit, digging my own rabbit holes further and further into the earth, that it is a wonder I ever emerged. Ultimately, the spell was broken and I was awakened, as if by a pneumatic drill that starts out as a peril within a dream but, as one wakes, becomes the sound of roadworks in the next street. I heard some material (it doesn't matter what: whatever woke me will wake only me; I think we all have our own, particular intrusive saviours) that I tried to co-opt to my own purposes but was so God-infused that it refused to be bent and, instead, bent and broke me.
The programme does enjoin me to look at myself in Steps Four, Eight, Ten, and Eleven, but the great injunction is:
Look, don't stare.