I love the enigmatic nature of koans. Like a sumi-e painting, they are structured to defy reasoning and conceptual thinking with what is essentially a riddle. The reader may interpret them as nonsensical stories with no inherent meaning, or they might be understood as the key that unlocks a door that leads to greater understanding to one’s truer nature.
As usual, the Zennist offers a great explanation:
Koans are set up in such a way that for those who have realized Mind to some degree it is easily seen at work in koans while for those who are ignorant of Mind it is not seen at all. What confronts the latter is paradoxical and will remain such until they eradicate the false thinking which prevents them from seeing what koans are meant to reveal.