To elaborate just a little...Bodhisattvas have often postponed their ascendance/disappearance into Nirvana in order to stay on Earth and use their talents, whether for teaching others the path or for healing, etc., to help others. Many Mahayanans believe there are countless bodhisattvas on Earth at any moment. There is a corollary Chinese concept involving minor teacher deities who walk among humans teaching academic, artistic, or moral lessons, according to their own natures.