Relation of the Word to the Father
“WHAT is conceived in the intellect is a likeness of the thing understood and represents its species; and so it seems to be a sort of offspring of the intellect. Therefore, when the intellect understands something other than itself, the thing understood is, so to speak, the father of the word conceived in the intellect, and the intellect itself resembles rather a mother, whose function is such that conception takes place in her. But when the intellect understands itself, the word conceived is related to the understanding person as offspring to father. Consequently, since we are using the term word in the latter sense (that is according as God understands Himself), the word itself must be related to God, from whom the word proceeds, as Son to Father.
~St. Thomas Aquinas: Compendium of Theology, 39