The Blessed One was once living at Kosambi in a wood of simsapa trees. He picked up a few leaves in his hand, and he asked the bhikkhus, “How do you conceive this, bhikkhus. Which is more, the few leaves that I have picked up in my hand or those on the trees in the wood?”
“The leaves that the Blessed One has picked up in his hand are few, Lord; those in the wood are far more.”
“So too, bhikkhus, the things that I have known by direct knowledge are more; the things that I have told you are few. Why have I not told them? Because they bring no benefit, no advancement in the Holy Life, and because they do not lead to dispassion, to fading, to ceasing, to stilling, to direct knowledge, to enlightenment, to Nibbana. That is why I have not told them. And what have I told you? This is suffering; this is the origin of suffering; this is the cessation of suffering; this is the way leading to the cessation of suffering. That is what I have told you. Why have I told it? Because it brings benefit, and advancement in the Holy Life, and because it leads to dispassion, to fading, to ceasing, to stilling, to direct knowledge, to enlightenment, to Nibbana. So bhikkhus, let your task be this: This is suffering, this is the origin of suffering, this is the cessation of suffering, this is the way leading to the cessation of suffering.”
(Samyutta Nikaya LVI, 31)