Thomas Boston, Works, 4:389-390:
Watch over your graces. Grace is that fire sent down from heaven into the hearts of sinners, which must not be neglected 2 Tim. 1:6. Our graces are subject to decay, though not to death. Though grace cannot die out of the garden of the heart, when once it is implanted, yet it may be overgrown and hid. It is a great pledge of the Lord’s love and every way precious; therefore to be watched, seeing it is in hazard.