God's knowledge of everything

Aquinas on how God knows everything by knowing himself:

Hence many ideas exist in the divine mind, as things understood by it; as can be proved thus. Inasmuch as He knows His own essence perfectly, He knows it according to every mode in which it can be known. (STh I.15.2 c. The "Summa Theologica" of St. Thomas Aquinas. Part I. QQ. I-XXVI. Literally translated by Fathers of the English Dominican Province. 2nd rev. ed. London: Burns Oates & Washbourne, 1920)