Thomas Aquinas’ thoughts culminate in the analysis of what thought is in itself. He reflects upon human thought and then upon God’s thoughts.
Human understanding is based on what can be perceived by the senses and captured in the imagination. The proper object of the human intellect is the ‘whatness’ or quiddity of the material thing. Aquinas is down-to-earth in being concerned about thoughts based on things that can be perceived.
The judgment of things is, however, based on innate first principles – principles infused into the human soul by God. We judge things through uncreated truth.
God is the efficient cause of all things. God is really related to creatures as their Creator, and their relationship with God is one of dependence. God knows his own essence and every creature as participating in his essence. Every creature has its own proper form in which it is like God. God knows the form or idea of every creature. In this way God both made the creature and knows the creature.
As human beings, we only know ourselves and are ourselves through God.