If Passion drives, let Reason hold the Reins.

Benjamin Franklin (1706–1790) American statesman, scientist, philosopher, aphorist

Poor Richard Improved (1749 ed.)
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The metaphor is not new with Franklin. Plato used a chariot allegory in his Phaedrus, where Reason is the charioteer, controlling a white horse of noble Passions and a black horse of unruly Passions. Buddha compared his mind to a wild elephant that once wandered where it wanted, but now was under control as if by a trainer.