I can’t remember where I got this, but when I find it I will add the source here immediately:

At the root of her spiritual life, the source of her power, is her doctrine of the “inner cell.” This cell, which she herself never left, consists, as it were, of  two compartments.They are knowledge of God and knowledge of self, summed up in the great twofold truth by which she was guided: “I am He Who is, and thou art she who is not.” This fertile principle of the knowledge of God and of self nourishes man’s spiritual life from the first stirrings of Divine Grace to the sublime heights of the mystic union.

At the beginning it is the root of virtue, for through the knowledge of the Divine Omnipotence and the nothingness of the creature the soul is brought to the fear of God, the beginning of wisdom, by which she turns away from those things that displease Him and does those He commands. Then, in gratitude for the benefits received, she begins to increase in the knowledge of God and of herself, and through this knowledge servile fear is gradually transformed into love. For, as God teaches St Catherine, “the soul should season the knowledge of herself with the knowledge of my goodness,” else she might fall into despair.

Yet at this stage her knowledge is far from perfect; it needs to be purified in temptation. “For one does not arrive at virtue except through knowledge of self, and knowledge of me, which knowledge is more perfectly acquired in the time of temptation, because then mans knows himself to be nothing.”

Knowledge, then is the mother of true humility, for it is inconceivable to the saint that a man should truly know himself to be a creature and not be humble. And this knowledge of self brings forth another virtue, patience, which Catherine calls the Queen of virtues and the marrow of charity, for it is “conceived in self-knowledge and in knowledge of my goodness to the souls, and brought forth by means of holy hatred and anointed with true humility.” Thus the supernatural life gradually unfolds through knowledge, for it is “in the house of self-knowledge, with holy prayer, where imperfections are lost.”