To trip means to stumble or fall as a consequence of striking one's foot against something and thereby losing one's balance. I recently tripped over a book which I placed on the floor next to my desk, and in the moment of tripping I was enlightened. I was not enlightened in the Buddhist sense of satori, but rather I experienced an intellectual "aha!" sort of enlightenment that caused me to understand the nature and causes of tripping. This was similar to the sudden understanding that caused Archimedes to shout "eureka!" and run naked through the street when he discovered the secret of how to measure the volume of an irregular solid, though in my case I did not run naked through the street. I simply mooned my neighbors out the window.

While I was still in the process of collapsing to the floor, it occurred to me that one is more likely to trip in familiar places than in unfamiliar surroundings. This is because one tends to be more cautious, and to depend on one's sense of sight, when walking in unfamiliar surroundings. On the other hand, when at home, or in other places where walking has become a matter of rote, one depends more on a conditioned sense of space, which one does not expect to undergo any radical changes. On does not bother to look where one is going, and even conscious knowledge that a change has taken place may be insufficient to bypass the subconscious mechanism by which one navigates in a familiar space. Changing the familiar is like putting a new coffee table in the middle of a blind man's living room.

...and then I hit the floor.