Zen purposes to discipline the mind itself, to make it its own master, through an insight into its proper nature. This getting into the real nature of one’s own mind or soul is the fundamental object of Zen Buddhism.
Zen is the spirit of a man. Zen believes in his inner purity and goodness. Whatever is superadded or violently torn away, injures the wholesomeness of the spirit. Zen, therefore, is emphatically against all religious conventionalism.
The contradiction so puzzling to the ordinary way of thinking comes from the fact that we have to use language to communicate our inner experience, which in its very nature transcends linguistics.
If you have attained something, this is the surest proof that you have gone astray. Therefore, not to have is to have, silence is thunder, ignorance is enlightenment.
