The storehouse of treasures opens by itself, you can take them and use them any way you wish.
Once I was taking a hike on a chilly day on a cliff overlooking the Pacific Ocean near Drake's Bay. I was having a conversation, it was windy, what I saw was mostly ocean and horizon. I didn't expect much from the view and wasn't paying much notice and then, far far out, there was a splash. And after that there were more splashes. Whales began appearing, jumping and breaching. The ocean, it seemed, was full of whales.
And another time the dog, who seemed to have acquired a maternal instinct in the springtime, brought in a very tiny baby vole. We kept it warm and fed it and suddenly, for all of us, it became clear that the ground had life underneath it. Our imaginations had expanded to include a vast world there, full of vole families, living inside the earth.
When I meditate, new worlds appear. Sometimes I notice something physical, a way I hold my face, something about how I'm breathing. Sometimes I notice my thinking, and I wonder how it was I came to believe that thing, so far from what I really believe. Sometimes it's the texture of reality that comes to me, how soft and nourishing this thing is that I had never noticed before, and the problems I had a moment before just fall off me. Sometimes I find myself trading places with a tree, a bird, and the koan shows me that my life is so much richer and more mysterious than I had been aware of.
So why is it one would meditate? These things are pointers to something I notice more and more: when one thing is revealed, something else comes into view. And the layers just go on and on. That's why I think meditation is an adventure. The territory is extensive, probably endless. There are moments when the view is a little vertiginous (vertigo inducing) but every step is fascinating. You can't see something until you see it, and each step shows you something new.