Strive with thy thoughts unclean before they overpower thee. Use them as they will thee, for if thou sparest them and they take root and grow, know well, these thoughts will overpower and kill thee. Beware! Suffer not their shadow to approach. For it will grow, increase in size and power, and then this thing of darkness will absorb thy being before thou hast well realized the black foul monster’s presence.
Blavatsky, H. P.