Obj. 3: Further, to believe is an act of the intellect, since its
object is truth. But assent seems to be an act not of the intellect,
but of the will, even as consent is, as stated above (I-II, Q. 15, A.
1, ad 3). Therefore to believe is not to think with assent.

_On the contrary,_ This is how "to believe" is defined by Augustine
(De Praedest. Sanct. ii).

_I answer that,_ "To think" can be taken in three ways. First, in a
general way for any kind of actual consideration of the intellect, as
Augustine observes (De Trin. xiv, 7): "By understanding I mean now
the faculty whereby we understand when thinking." Secondly, "to
think" is more strictly taken for that consideration of the
intellect, which is accompanied by some kind of inquiry, and which
precedes the intellect's arrival at the stage of perfection that
comes with the certitude of sight. In this sense Augustine says (De
Trin. xv, 16) that "the Son of God is not called the Thought, but the
Word of God. When our thought realizes what we know and takes form
therefrom, it becomes our word. Hence the Word of God must be
understood without any thinking on the part of God, for there is
nothing there that can take form, or be unformed." In this way
thought is, properly speaking, the movement of the mind while yet
deliberating, and not yet perfected by the clear sight of truth.
Since, however, such a movement of the mind may be one of
deliberation either about universal notions, which belongs to the
intellectual faculty, or about particular matters, which belongs to
the sensitive part, hence it is that "to think" is taken secondly for
an act of the deliberating intellect, and thirdly for an act of the
cogitative power.