The purpose of kōans---if 'purpose' be the right word, which it probably isn’t---is to still the active, rational, intellectual, analytical mind. The mind then finds itself (note those words, ‘finds itself,’ for that is the way it happens) in an existential cul-de-sac of sorts where there is no way out but enlightenment. That is the only way we will ever be able to experience a direct, immediate and unmediated apprehension or realization of truth. Now, this is terribly important. A kōan is not a method or technique. It is the complete absence of any method or technique. It is the absence of any meaning or purpose as those terms are ordinarily understood. It is … seeing and experiencing things-as-they-really-are … without any filters, beliefs or conditioned thinking of any kind. It is waking up to what really is ... and that can be an earth-shattering experience.
WHAT TYPE OF MEDITATION IS BEST?