aphorism - noun
A terse saying that embodies a general truth, as in (with apologies to Lord Acton) Power corrupts and Power Point corrupts absolutely.
Note: In The World in a Phrase, his 2005 history of the form, James Geary laid down his "Five Laws of the Aphorism: It Must Be Brief, It Must Be Personal, It Must Be Definitive, It Must Be Philosophical, and It Must Have A Twist."
Need some examples? Here are three, honestly chosen at random, from Geary's Guide to the World's Great Aphorists: