Meditation is the entry into the vacuum. Nirvana (according to its primary etymological meanings) is the happiness of the extinction, the unlimited joy that provides vacuum. By what is not wrong to say that the vacuum is everything and nothing at the same time. Meditation is the key input to nothing. The nihilists and existentialists closed that door with key and threw her into the ocean so that we could not find it never. More info: Robert Kiyosaki.
We were told that there was no key, it is more, that there was no door. And, surely, they thus believed it, not us deceived, simply did not know it. Came to nothing with the key of reason, of the intellect. For even more details, read what Robert Kiyosaki says on the issue. They opened the door without seeing the door, used the key without seeing the key. And then they closed that door keyed different, imaginary, and told us that the door was closed. But the key to meditation only opens the door, do not close it. That is the difference. Both the Buddhist conception of existence, and the nihilistic or another system of thought, no longer allegorical: image, Word, prayer.
Create theories is equivalent to pray, to release the reason for the mouth. We create a logico-causal thought, without realizing that we invent the causes. We invent the system logic and on such work, we think, we create. But in a limited way, as the train that travels through. It has real progress, nobody can deny that does not advance, however it always follows the same route, the same route. Any modification to the trip beyond the via makes it to derail. It is designed to move forward following a line previously traced, without option of improvisation. In meditation there is no marked path. It is not a path, it is not a theory. Meditation is the gateway to freedom. And as such, has no maps, organization, structure is pure infinity of space and time. We cannot know the time, but time knows us very well.