The central teachings of the Buddha are called the Four Noble Truths (cattàri ariyasaccàni). The first of these truths is that ordinary existence is suffering (dukkha). The second is that suffering is caused by ignorance (avijjà) and craving (taõhà). The third is that suffering can be transcended. And the fourth Noble Truth is the way and means to transcend suffering, which is the Noble Eightfold Path. It seems that the Buddha based this schema on the procedure used by ancient Indian physicians. The physician would understand that the patient was ill by observing his or her symptoms. Using his knowledge and experience and questioning patients, he would try to find out what they had been doing or had eaten or what had happened to them that was making them ill. He would then encourage his patients by telling them that their health could be restored. And finally he would prepare the appropriate medicine, give it to the patient and instruct him or her how to take it.
The Buddha said many times that his role was to show the way out of suffering: `One thing and one thing only do I teach, suffering and how to end suffering' (M.I,140). Once a monk approached him and insisted he answer questions about the origins and extent of the universe and other speculative matters. The Buddha refused, saying that humanity was like a man pierced by a poison arrow and that the good physician's role was to remove this arrow, not to tell the afflicted man what type of wood the arrow was made from, what type of feather was used for the flight or the biography of the man who shot it. He then said: `And why do I not answer all your questions? Because they are not useful, they do not help in living the holy life, they do not lead to turning away, to dispassion, to stilling, to peace, to higher knowledge or to Nirvana. And what do I teach? Suffering, its cause, its transcendence and the way leading to its transcendence. And why do I teach this? Because it is useful, it helps in living the holy life, it leads to turning away, to dispassion, to stilling, to peace, to higher knowledge and to nirvana' (M.I,431).