Zen draws on the Buddhist tradition of belief that the world as we experience it — both individually and between ourselved — is an illusion, and that gain a true understanding of what is, what it is like, and so on requires disengagement from the illusion. Logical thinking demands interaction with the illusion. Koans are meant to present situations/questions/etc. that are nonsensical in terms of logical understanding, the underlying goal being to push the ponderer to abandon logic and thus disengage with the illusion that is the world.
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