Source:http://www.brahmacarya.info/2010/12/victims-of-the-mind/

Even though a woman be made of wood or stone, she becomes attractive when decorated. One becomes sexually agitated even by touching the form. Therefore one should not trust his mind, which is so fickle that it can give way to enemies at any moment. The mind is always accompanied by six enemies — namely, kama, krodha, mada, moha, matsarya and bhaya — that is, lust, anger, intoxication, illusion, envy and fear. Although the mind may be merged in spiritual consciousness, one should always be very careful in dealing with it, just as one is careful in dealing with a snake. One should never think that his mind is trained and that he can do whatever he likes. One interested in spiritual life should always engage his mind in the service of the Lord so that the enemies of the mind, who always accompany the mind, will be subdued. If the mind is not engaged in Krsna consciousness at every moment, there is a chance that it will give way to its enemies. In this way we become victims of the mind.

- Excerpt from Srila Prabhupada's commentary to Sri Caitanya-caritamrita, Madhya 11.10