If we stop chopping at the branches of this problem and strike more directly at the root of the tree, not surprisingly we find lust lurking furtively there. Lust is an unsavory word, and it is certainly an unsavory topic for me to address, but there is good reason why in some traditions it is known as the most deadly of the seven deadly sins.

Jeffery R. Holland 

Combating Pornography

http://www.lds.org/family/family-well-being/combating-pornography/audiences/individuals/place-no-more-for-the-enemy-of-my-soul?lang=eng