/summa/XP/XPII/XP_Q52:
We must now consider the impediment of the condition of slavery. Under this head there are four points of inquiry:
(1) Whether the condition of slavery is an impediment to matrimony?
(2) Whether a slave can marry without his master's consent?
(3) Whether a man who is already married can make himself a slave without his wife's consent?
(4) Whether the children should follow the condition of their father or of their mother?