It seems that only Zen Buddhism has the practice/ritual of the koan. I was wondering if the functions of the koan ritual in Zen are 'taken care of' in some way in other religions. IOW I don't think there is a direct parallel in other religions, where a sentence or short dialogue or question that is hard to logically interpret is given to a 'student' who then works on finding a meaning or response that is approved by the master. It seems to me Koans are challenging naive realism in language, cognitive habits, literalness, and even left brain approaches to understanding. Are there practices in other religions that go at these issues or whatever issues/problems you think the koan ritual is attempting to solve?