Before Zen spread to Japan and was known as Zen, it was in China and known as Chan. Here 8th Century Chan Master Hui Hai gives us a wonderful short-cut to enlightenment or nirvana:
Hui Hai: The Shurangama Sutra says: ‘Perceptions employed as a base for building up positive concepts are the origin of all ignorance (avidya); ‘perception that there is nothing to perceive – that is nirvana, also known as deliverance.’
Questioner: What is the meaning of ‘nothing to perceive’?
Hui Hai: Being able to behold men, women and all the various sorts of appearances while remaining as free from love or aversion as if they were actually not seen at all – that is what is meant by ‘nothing to perceive’.
Questioner: That which occurs when we are confronted by all sorts of shapes and forms is called ‘perception’. Can we speak of perception taking place when nothing confronts us?
Hui Hai: Yes.
Questioner: When something confronts us, it follows that we perceive it, but how can there be perception when we are confronted by nothing at all?
Hui Hai: We are now talking of that perception which is independent of there being an object or not. How can that be? The nature of perception being eternal, we go on perceiving whether objects are present or not. Thereby we come to understand that, whereas objects naturally appear and disappear, the nature of perception does neither of those things; and it is the same with all your other senses.
[Tom: what is being signified here by ‘eternal’ perception that is independent of objects? :-)]
Questioner: When we are looking at something, does the thing looked at exist objectively within the sphere of perception or not?
Hui Hai: No, it does not.
Questioner: When we (look around and) do not see anything, is there an absence of something objective within the sphere of perception?
Hui Hai: No, there is not.
Questioner: When there are sounds, hearing occurs. When there are no sounds, does hearing persist or not?
Hui Hai: It does.
Questioner: When there are sounds it follows that we hear them, but how can hearing take place during the absence of sound?
Hui Hai: We are now talking of that hearing which is independent of there being any sound or not. How can that be? The nature of hearing being eternal, we continue to hear whether sounds are present or not.
Questioner: if that is so, who or what is the hearer?
Hui Hai: It is your own nature, which hears, and it is the inner cogniser who knows.