Thomas Aquinas offers the same reason for coinherence among the persons: “The Father is in the Son by His essence, forasmuch as the Father is His own essence, and communicates His essence to the Son not by any change on His part. Hence it follows that as the Father’s essence is in the Son, the Father Himself is in the Son; likewise, since the Son is His own essence, it follows that He Himself is in the Father in Whom is His essence…. And the same applies to the Holy Ghost.”54
