The Snake Catcher
There was once snake catcher who once went to the mountains. Due to the winter cold and heavy snow, many very big snakes lay motionless, as if they were dead.
The snake-catcher picked up one of these seemingly lifeless snakes and took it to Baghdad, with the purpose of using it for a show. Showing it off, he made big claims as to how he had brilliantly captured the snake.
However, when the sun began to shine and its warmth cloaked the snake, the coldness in its body disappeared. The signs of life were soon apparent and when the snake began to move, the snake-catcher and all those around, fled.
Our Nafs is like that snake. With Tazkyia (purification), Mushaqqat (effort), our nafs (self) becomes frozen. It appears to be dead. But give it a little heat from the fire of sin and it will bite again. A little exposure to some past sins and the nafs swings back to life.
We should not think that we have killed our nafs and thus become unmindful. Yes, with some mujahadah (striving), suhbat (company) of the Sheikh, tilawat (recitation) of the Qur'an, Dikrullah, following Deen and Shariah and in building up that contact and love for Allah Ta'ala and Rasulullah (salAllahu alayhi wasalam), the nafs can be frozen. However, a little taste of sin revives the evil nafs.
Jalaluddin Rumi (rahmatullahi alaiyh)