So saving grace, converting grace, for Augustine, is God's giving us a sovereign joy in God that triumphs over all other joys and therefore sways the will. The will is free to move toward whatever it delights in most fully, but it is not within the power of our will to determine what that sovereign joy will be.
John PiperIgnatius, when he heard the clock strike, would say, "Now I have another hour to answer for." (Eph. 5:16)
John PiperThis is the centre of the gospel - this is what the Garden of Gethsemane and Good Friday are all about - that God has done astonishing and costly things to draw us near.
John Piper