Hakuin Ekaku: What is Enlightenment?

Hakuin Ekaku treated enlightenment as square one in his journey to reinvent the Zen practice. But what exactly makes a person "enlightened?"
Sources:
"Wild Ivy (Itsumadegusa 壁生草): The Spiritual Autobiography of Zen Master Hakuin"
terebess.hu/zen/Hakuin_WildIv...
"Hakuin on Kensho: The Four Ways of Knowing"
terebess.hu/zen/mesterek/kens...
Some Famous Koans:
terebess.hu/zen/mesterek/clea...

[@SociallyAwkwardPatriarchClone]

There is no way I can reach enlightenment, I can't even have a cohesive thought.