Once Fire met Water on the banks of the Ganga to settle an age-long dispute between them  as to which of them was powerful. Water asserted its prowess by quoting ample incidents in support of its ability to put down even big fires and told that Fire could not do anything to water save only when water is confined to small vessels.

That much of a hint was enough for Fire. Knowing fully well that it could not score a direct victory over Water, Fire digressed a bit and began to talk about the welfare of Water. It said, “My dear Water, look! how much dirt is there around you. Why not you just step into this beautiful golden vessel. It will help you to remain ever pure and clean.” Water was naturally tempted; and no sooner did he jump into the golden vessel, than Fire boiled it with all its might. As it was becoming warmer and warmer, Water found everything comfortable. When once the boiling point was reached, water felt the torture and began to brood over its folly.

Sivananda Says:
It is all a parable.
Like the Water, your pure thoughts, your discriminative intellect, your reason, nay, your Mumukshutva and love for soul is.
Nothing can defile it as long as it goes its own way. It is ever pure and clean. It has got the power to cleanse everything.

Like the Fire, your love for flesh is. Fire is ferocious. So too, love for flesh. It is equally powerful like Water. If one annihilates the other all at once, the other has got the ability to torture the first.

O Man, safeguard your Mumukshutva, your reason, your discriminative intellect. It is ever powerful. The love for flesh tempts you to seek little comforts. You feel you are comfortable and unattached to the comforts at the same time. The comforts increase slowly and slowly like the water getting warmer and warmer. You feel all right. But, when it comes to the boiling point, you feel. You brood over your follies. You become a complete slave to the luxurious things. You lose your power and ability to put down the fire of lust, greed, etc.

In short, you are lost.
The love for flesh is ever on the alert to seek its little comforts. It pleads and tempts at every moment your Sattvic mind and intellect. Never, never hear it. Be careful. Assert the supreme power of your aspiration, your love for soul. You will be intact and unaffected by the fire that is the lower nature in you, that is the old evil Vasanas