First there is a mountain, then there is no mountain, then there is....
The famous saying of Ch'ing-yüan Wei-hsin (Seigen Ishin):
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 are not waters. But now that I have got its very substance I am at rest. For it's just that I see mountains once again as mountains, and waters once again as waters.