De Profundis

But with the dynamic forces of life, and those in whom those dynamic forces become incarnate, it is different. People whose desire is solely for self-realisation never know where they are going. They can't know. In one sense of the word it is of course necessary, as the Greek oracle said, to know oneself: that is the first achievement of knowledge. But to recognise that the soul of a man is unknowable, is the ultimate achievement of wisdom. The final mystery is oneself. When one has weighed the sun in the balance, and measured the steps of the moon, and mapped out the seven heavens star by star, there still remains oneself. Who can calculate the orbit of his own soul? When the son went out to look for his father's asses, he did not know that a man of God was waiting for him with the very chrism of coronation, and that his own soul was already the soul of a king.

...De Profundis, Oscar Wilde