the will (without any metaphysical refining) is plainly, that by which the mind chooses any thing. The faculty of the will is that faculty or power, or principle of mind, by which it is capable of choosing: an act of the will is the same as an act of choosing or choice.Part I Sect I, Freedom of the Will
The will is that by which we both sin and live righteously. But unless the will itself is freed by God's grace from servitude, by which it is made a servant to sin, and is helped to overcome the vices, it is impossible for mortals to live righteously and piously.Retractationes, bk 1 c9 n4