The main reason for Zen's unexpectedness or incalculability comes from transcending conceptualization. It expresses itself in the most impossible or irrational manner; it does not allow anything to stand between itself and its expression. In fact, the only thing that limits Zen is its wanting to express itself. But this limitation is imposed upon everything human and indeed upon things divine as long as these are to be made intelligible.

The spirit of Zen is then the going beyond conceptualization, and this means to grasp the spirit of the most intimate manner. This in turn means the disregarding to a certain extent of all technique. The idea may be better expressed by stating that Zen holds in itself something which eludes all systematized technical skill but which is to be somehow grasped in order to come in the closest possible touch with Life, all-generating and all-pervading and all-invigorating.

--from "The Awakening of Zen" by Daisetz Teitaro Suzuki