In the next place we must consider matrimony absolutely; and here we must treat (1) of the betrothal; (2) of the nature of matrimony; (3) of its efficient cause, namely the consent; (4) of its blessings; (5) of the impediments thereto; (6) of second marriages; (7) of certain things annexed to marriage.

Under the first head there are three points of inquiry:

A1 What is the betrothal?

A2 Who can contract a betrothal?

A3 Whether a betrothal can be canceled?