One of my dictionaries defines aphorism as a short pithy statement or maxim. I’m not sure if one can consider them a literary form, but I delight in them.
“It is as easy to dream a book as it is hard to write one.” (Balzac)
“Man shall not live by bread alone.” (Matthew 4:4)
“You can pretend to be serious; you can’t pretend to be witty.” (Sacha Guitry)
“Happy families are all alike; every unhappy family is unhappy in its own way.” (Tolstoy)
“Man is least himself in his own person. Give him a mask and he will tell you the truth.” (Oscar Wilde)
“Power is much more easily manifested in destroying than in creating.” (Wordsworth)
If I can slip them into my own writing it gives me pleasure.
“The easiest part of being a parent is loving your child. The hardest part is convincing them you do.” (The Most Important Thing)
“The more I knew of the world the more I knew I knew it not.” (Crispin: Cross of Lead)
“Roads at night are always new.” (Night Journeys)
“Asking someone to say they love you is like buying yourself a birthday present. It’s more than likely exactly what you want. But it must make you feel awfully sad to get it.” (Sometimes I Think I Hear My Name)
Readers are welcome to supply their own favorite aphorism in the comments.