Sentence:  Thwackum, on the contrary, maintained that the human mind, since the fall, was nothing but a sink of iniquity, till purified and redeemed by grace....The favourite phrase of the former, was the natural beauty of virtue; that of the latter, was the divine <WSD>power</WSD> of grace. 
Meaning of the word marked with <WSD> tags:  Ability to affect or influence.