- Material: answers "Out of what am I?"
answer: "My body."
- Formal: answers "What am I?"
answer: "My soul. It makes me actual."
My conception is my existence, and existence is not extrinsic to myself. My form is what makes me actual, just as the form of the Statue of David is what makes it actually the Statue of David and not a formless lump of marble.
cf. St. Thomas Aquinas's short work (opusculum) De Principiis Naturæ
Commentating on Aristotle's Metaphysics book 5, St. Thomas Aquinas shows (Sententia libri Metaphysicae lib. 5 l. 3 "All Causes Reduced to Four Classes" ) that there can a hierarchy of causes:
785. (1) For one cause is said to be prior and another subsequent; and causes are prior or subsequent in two ways: (1) In one way, when there are many distinct causes which are related to each other, one of which is primary and remote, and another secondary and proximate (as in the case of efficient causes man generates man as a proximate and subsequent cause, but the sun as a prior and remote cause); and the same thing can be considered in the case of the other classes of causes. (2) In another way, when the cause is numerically one and the same, but is considered according to the sequence which reason sets up between the universal and the particular; for the universal is naturally prior and the particular subsequent.
cf. also l. 2 "The Four Classes of Causes. Several Causes of the Same Effect. Causes May Be Causes of Each Other. Contraries Have the Same Cause"
So, the sun is a remote efficient cause of me,* and my parents** are a proximate efficient cause of me.
*The sun helped plants grow so my parents could live and procreate me.
**Aristotle seems to have thought the father was the only proximate efficient cause, but St. Thomas knew the woman wasn't completely passive in procreation; she contributes the material out of which my body is made, so she is also an efficient cause. Two efficient causes can work toward the same end, just as multiple builders can build the same house.