From Fragment H found in Clement of Alexandria:
For the many spirits dwelling in the heart do not permit it to become pure: rather, each of them performs its own acts, violating it in various ways with improper desires. And in my opinion the heart experiences something like what happens in a caravansary. For the latter is full of holes and dug up and often filled with dung, because while they are there, people live in an utterly vulgar way and take no forethought for the property since it belongs to someone else. Just so, a heart too is impure by being the habitation of many demons, until it experiences forethought.