The "South Indian Monkey Trap" was developed by villagers to catch the ever-present and numerous small monkeys in that part of the world. It involves a hollowed-out coconut chained to a stake. The coconut has some rice inside which can be seen through a small hole. The hole is just big enough so that the monkey can put his hand in, but too small for his fist to come out after he has grabbed the rice.
Tempted by the rice, the monkey reaches in and is suddenly trapped. He is not able to see that it is his own fist that traps him, his own desire for the rice. He rigidly holds on to the rice, because he values it. He cannot let go and by doing so retain his freedom. So the trap works and the villagers capture him. iii
Dan Thompkins. (2008). Sermons of Dan Thompkins.