Orson F. Whitney
“What is Sin? Sin is the transgression of divine law. A man sins when he violates his conscience, going contrary to light and knowledge—not the light and knowledge that comes from his neighbor, but that which has come to himself. He sins when he does the opposite of what he knows to be right. Up to that point he only blunders. One may suffer painful consequences for only blundering, but he cannot commit sin unless he knows better than to do the thing in which the sin consists.” (Cowley & Whitney on Doctrine, pp. 435-436 as taken from Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 119)