/summa/TP/TPII/TP_Q33:
We have now to consider the mode and order of Christ's conception, concerning which there are four points of inquiry:
(1) Whether Christ's body was formed in the first instant of its conception?
(2) Whether it was animated in the first instant of its conception?
(3) Whether it was assumed by the Word in the first instant of its conception?
(4) Whether this conception was natural or miraculous?