You seem to have answered your own question as to the general myth regarding centaurs, that they were normally represented as being driven by the "beast" half of their nature and living in wild, Dionysian fashion. (Dionysus was the Greek god of wine and wild feelings.)
There was one centaur in Greek mythology, however, that stood out as different from that traditional representation. The centaur Chiron was noted for his wisdom and served as an instructor to famous Greek characters like Achilles, Jason and Heracles.
