There are three teachers for every one. The first, are the parents. They sacrifice their lives to give comfort to their children in a practical way by taking good care of them. The second teacher is preceptor who guides the student in exercising his discrimination and taking the right path towards realizing the divinity within him. The third teacher is your own conscience. This is divine and always helps one to take the correct decision.
(From : Sai Veda, The Word of God, sayings of Bhagavan Sri Sathya Sai Baba)