The term Zen or in Sanskrit dhyāna is more about a process than the actual enlightenment of Siddhartha. Supposedly, Bodhidharma said: Seeing your true nature is Zen. Unless you see your nature, it’s not Zen.
The process of Zen leads up to seeing or intuiting this nature or svabhāva. Still, this nature transcends even Zen and what the human imagination can construct. This is “book Zen” but also Buddhism. Words and the ideas they evoke are not the same as directly seeing one’s nature. Far from it.
Zen as a process is more about getting the student to drop analytical thinking and turn to the direction of intuition. This is somewhat like shifting from over-reliance on the left hemisphere of the brain and shifting over to the right hemisphere where lies intuition which supersedes a jumble of ideas.
The difficulty of achieving intuition should not be underestimated. It is not easy to make the transition from analytical thinking to direct intuition.
The true transmission of the Dharma only obtains by a path of intuition or Zen. Our all-too-human efforts will fail, but that is not entirely a bad thing from Zen’s perspective. This is coming to Zen’s Great Doubt 大疑 in which all human efforts fail. It is only in this emptiness that one is for the first time open to being transmitted by the Buddha.