/summa/FP/FPIII/FP_Q33:
We now consider the persons singly; and first, the Person of the Father, concerning Whom there are four points of inquiry:
(1) Whether the Father is the Principle?
(2) Whether the person of the Father is properly signified by this name "Father"?
(3) Whether "Father" in God is said personally before it is said essentially?
(4) Whether it belongs to the Father alone to be unbegotten?