"Once when I was off on a Zen retreat in Kyoto, the ancient capital of Japan, I was very surprised to see another Westerner there--in fact he was a Roman Catholic priest doing Zen practice--and we became friends. His name was Father William Johnston. He’s written many books and he broadened my perspective considerably. As a Christian, he had learned a lot from the techniques of meditation that come from the Buddhist tradition, and it had allowed him to deepen his Christianity. Through him I learned that the experiences that I was having in doing Buddhist meditation were part of a much broader worldwide phenomenon: that meditation, in fact, existed in Christianity, Judaism, Islam. That it was, in a slightly different form, central in the shamanic practices of our tribal ancestors. That it is indeed a global and universal thing, and that although the particular customs and doctrinal systems--the belief systems--of the various world religions differ dramatically, the contemplative or meditative core is virtually universal.
Father Johnston had a vast library of comparative mysticism--the writings of the meditation masters of the world--and he let me read in that library. So I got to see what I was doing in Buddhist meditation in a much broader context. He also got me interested in the scientific study of meditative states. He had friends at a Buddhist university who were studying the brainwaves of Zen meditators, and he took me to their research lab. They hooked us both up to their equipment and were utterly amazed to see that a Roman Catholic priest produced the same kind of brainwaves as a 30-year Zen meditator. But of course it’s not surprising at all, given the universal nature of the meditative experience."