Once, Prabhupada told a story about an Indian train. Local trains in India are often packed. In almost any third world country, you'd learn what the word “packed” means. So, you have a nice seat on the crowded train, and then some skinny guy comes to sit next to you. You try to ignore him, but you know he wants to sit down.
There is no room, but he smiles at you, then plops down and wiggles around between you and the next person. You try to help by making some room for him. Suddenly he calls his little kid, and he lets his kid sit with him. And then you’re moving towards the edge of the seat. Then he brings another kid and he finally gets three kids sitting next to you. Next, his fat wife comes and then you give up your seat.
It all started because you had a little sympathy and let this guy sit down in the first place. In this way, Srila Prabhupada said, if you allow maya even an inch to enter, she knows how to take over everything.
Ref: Memories and Anecdotes of a Modern - Day Saint
by Siddhanta Dasa