For the sake of those crucial experiences Zen Buddhism has struck out on paths which, through methodical immersion in oneself, lead to one’s becoming aware, in the deepest ground of the soul, of the unnamable Groundlessness and Qualitylessness˙nay more, to one’s becoming one with it.

I mean Dhyana Buddhism, which is known in Japan as " Zen " and 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.