A set of "old sayings," that seem to contradict one another.

You can't tell a book by its cover - Where there's smoke, there's fire
Better safe than sorry - nothing ventured, nothing gained
A stitch in time saves nine - haste makes waste
A penny saved is a penny earned - you can't take it with you
He who hesitates is lost - fools rush in
Two heads are better than one - too many cooks in the kitchen spoil the broth

I'm sure there are more out there. I also cannot believe that people planned or justified their actions on the basis of these contradictory sayings.

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Source: The list came from Carl Sagan's The Demon Haunted World, one of my personal favourite titles.