What is an aphorism, and why is it important?

A clever observation that generally contains great truth

Aphorisms are really clever little sayings that actually contain a profound truth. They were extremely popular during Revolutionary American Literature, with the publishing of Poor Richard's Almanac. They remain popular today in the form of bumper stickers and memes.

Have you ever said these aphorisms:

An apple a day keeps the doctor away One bad apple ruins the bunch All the glitters is not gold YOLO