According to Wisdom Quarterly: American Buddhist Journal: In Buddhism, the Buddha spoke of four things that should not be contemplated for too long as they would sooner lead to derangement than to a sensible solution:
"There are these Four Imponderables that should not be pondered because to do so would cause one to become vexed and mentally unhinged.
- The range of [influence of] a buddha is imponderable and should not be pondered because to do so would cause one to become vexed and mentally unhinged.
- The range of jhana of a person immersed in meditative-absorption [the powers one is able to obtain by way of the absorptions]...
- The [mysterious] working out of karma...
- A first cause or origin of the world...
"These are the Four Imponderables that should not be pondered because to do so would cause one to become vexed and mentally unhinged."