Every sin is preceded by a sinful thought which is preceded by a sinful desire. Desires, then, become the defining characteristic of one's spiritual integrity. However, concerning some sins, the Law of Moses restricted one's action but said nothing of one's thoughts or desires. The higher law teaches that evil thoughts and desires are just as destructive. Therefore the anger which encourages the premeditation which prompts the murder must be proscribed. The lust which encourages the sensual thought which prompts the adulterous act must be avoided. It's no longer a law of "Thou shalt not do this, but you can think whatever you want!" The new law warned against evil thoughts and desires. Alma was ahead of his time when he counseled, yea, let thy thoughts be directed unto the Lord; yea, let the affections of thy heart be placed upon the Lord forever (Alma 37:37). James Allen said
"A man does not come to the almshouse or the jail by the tyranny of fate or circumstance, but by the pathway of groveling thoughts and base desires. Nor does a pure-minded man fall suddenly into crime by stress of mere external force; the criminal thought had long been secretly fostered in the heart, and the hour of opportunity revealed its gathered power. Circumstance does not make the man; it reveals him to himself." (As a Man Thinketh as taken from The Miracle of Forgiveness, p. 105)
Bruce C. Hafen
"Moses and other Israelite leaders at times tried to teach the broad, positive doctrine of the higher law, but over time the lower law tended to emphasize negative restrictions on conduct—have no other gods, do not commit adultery. This emphasis is less concerned with motive or purpose, less demanding that we do anything affirmative, much less be anything that extends beyond what we are. The contrast with the higher law is staggering: 'Love thy wife with all thy heart' (DC 42:22); and 'Be ye therefore perfect.' (Matthew 5:48.) The higher law asks not only for new behavior; it asks for a new heart." (The Broken Heart, p. 162)
Neal A. Maxwell
"Further, the presence of the Holy Ghost in one's life, insofar as it reshapes our desires and our appetites, can move us from a position in which, at first, we wisely avoid temptations, to a point finally from which the things alien to the Spirit of God are diminished in their attractiveness. Just as what is at first a duty can later become a delight, so the dangerous things for which we may now hunger can be replaced by desires for things that are not only harmless, but that will also help us." (That My Family Should Partake, p. 83 – 84)
David O. McKay
"The greatest battles in life are fought within the silent chambers of the soul." (Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 415)