Whether the gift of understanding is in all who are in a state of grace?

Objections

Objection 1 : It would seem that the gift of understanding is not in all who are in a state of grace. For Gregory says (Moral. ii, 49) that "the gift of understanding is given as a remedy against dulness of mind." Now many who are in a state of grace suffer from dulness of mind. Therefore the gift of understanding is not in all who are in a state of grace.
Objection 2 : Further, of all the things that are connected with knowledge, faith alone seems to be necessary for salvation, since by faith Christ dwells in our hearts, according to Eph. 3:17. Now the gift of understanding is not in everyone that has faith; indeed, those who have faith ought to pray that they may understand, as Augustine says (De Trin. xv, 27). Therefore the gift of understanding is not necessary for salvation: and, consequently, is not in all who are in a state of grace.
Objection 3 : Further, those things which are common to all who are in a state of grace, are never withdrawn from them. Now the grace of understanding and of the other gifts sometimes withdraws itself profitably, for, at times, "when the mind is puffed up with understanding sublime things, it becomes sluggish and dull in base and vile things," as Gregory observes (Moral. ii, 49). Therefore the gift of understanding is not in all who are in a state of grace.