It was not lawful that he should think to separate himself from Mary for this, that she brought forth Christ as yet a Virgin. And herein may the faithful gather, that if they be married, and preserve strict continence on both sides, yet may their wedlock hold with union of love only, without carnal; for here they see that it is possible that a son be born without carnal embrace.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: de Cons. Evan., ii, 1