Before I had studied Zen for thirty years, I saw mountains as mountains and waters as waters. When I arrived at a more intimate knowledge, I came to the point where I saw that mountains are not mountains and waters not waters. But now that I hve got to the very substance I am at rest. For it is just that I see mountains once again as mountains and waters once again as waters.

So, the difference between dream experience and waking experience is momentous, but there’s no way of telling one from the other until something happens and you wake up, for example, and even then you’ve got a serious problem. So, I tried to show that all classical philosophical questions are like that; that you’ve got a difference which is un-empirical; you can’t tell the difference, and yet the difference is momentous in a certain way, and that’s what got me going. I think that my positivistic teachers felt that philosophy should be like science and it should all be a matter of observation and verification as to whether something goes this way or that. But I thought, all genuine philosophical distinctions are invisible in that kind of way.