[Haskell-cafe] Why Kleisli composition is not in the Monad signature?

Hi, The Monad class makes us define bind (>>=) and unit (return) for our monads. Why the Kleisli composition (>=>) or (<=<) is not made a part of Monad class instead of bind (>>=)? Is there any historical reason behind this? The bind (>>=) is not as elegant as (>=>), at least as I find it. Am I missing something? - Damodar