What does Buddhism mean by "Enlightenment"?
Enlightenment is a state of perfect knowledge or wisdom, combined with infinite compassion. Knowledge in this case does not mean merely the accumulation of data or a description of the world of phenomena down to the finest details. Enlightenment is an understanding of both the relative mode of existence (the way in which things appear to us) and the ultimate mode of existence (the true nature of these same appearances). This includes our own minds as well as the external world. Such knowledge is the basic antidote to ignorance and suffering.
But by ignorance we do not mean a simple lack of information. Rather we mean a distorted vision of reality that makes us think that what we see around us is permanent and solid, or that our ‟self” is a real, autonomous entity. This leads us to mistake fleeting pleasures or the alleviation of pain for lasting happiness. Such ignorance also makes us attempting to build our happiness on others' misery.
We are drawn to what satisfies our ego and are repulsed by what might harm it. Thus, little by little, we create ever-greater mental delusion until we behave in a totally egocentric manner. Ignorance perpetuates itself and our inner peace is destroyed.
Buddhism's form of knowledge is the final antidote to suffering. In this sense, it seems that knowing the brightness of stars or the distance between them may be very interesting in itself, but it cannot teach us how to become better people.
Once, a man asked the Buddha some questions about cosmology. In reply, he picked up a handful of leaves and asked: ‟Are there more leaves in my hands, or in the forest?” ‟There are more in the forest, of course,” replied the man. The Buddha went on: ‟Well, the leaves in my hand represent the knowledge which leads to the end of suffering”. In this way, the Buddha showed that certain questions are superfluous. The world has limitless fields of study, as numerous as the leaves of the forest. But if what we want more than anything else is Enlightenment, then it is better to concentrate entirely on that aim and gather together only the knowledge that is directly relevant to our quest.