2. Again, acts and habits seem to belong to the same kind of life. But

to teach is an act of wisdom, for the Philosopher says: "The proof that a man knows is that he is able to teach." Since, then, wisdom—that is, knowledge—pertains to the contemplative life, it would seem that teaching also must pertain to the contemplative life.

But habits and acts agree in their object, and consequently the argument just given is based upon the material of the interior concept. For the capacity for teaching is possessed by a wise or learned man just in proportion as he can express in outward words the concepts of his mind and so be able to bring home a truth to someone else.