For Orientals these mysterious formulae are clear and familiar truths, but for us they are completely bewildering... Dhyana Buddhism, which is known in Japan as "Zen"... is not speculation at all but immediate experience of what, as the bottomless ground of Being, cannot be apprehended by intellectual means, and cannot be conceived or interpreted even after the most unequivocal and incontestable experiences: one knows it by not knowing it.