The interesting thing about them is that they can be valid in a practical sense, yet render themselves invalid- so they're true, but false. Self-referencing always causes problems, paradoxes, and I find them to be a fascinating insight into the human condition (being both the sculptor and the sculpture, observer and participant, etc)
Actions speak louder than words / The pen is mightier than the sword Knowledge is power / Ignorance is bliss What will be, will be / Life is what you make it Many hands make light work / Too many cooks spoil the broth