"Know Thyself" is the threshold to Sophia. In the Gnostic Gospel of Saint Thomas, Sophia is called "The silence beyond comprehension." Sophia means wisdom, "to know" in Greek.
In early Christianity, Sophia was, like the Shekinah of Judaism, the female aspect of God. Churches were dedicated to Her, among them the great Basilica of Hagia Sophia in Istanbul. Gnostic mystics believed the divine could not be realized with the mind, but only accessed through ecstatic inner experience - personal gnosis.