I'll quote Shibayama Roshi's translation of a famous koan here from the Record of Baso, found in his Teisho on the Koan 'Mind is Buddha' page 214 of the The Gateless Barrier*, but before I do, I'll reiterate, that Koans are not parables, but training tools, take notice pof the dialogue described to see that, but for the purpose of what I'll say here, I'll use this as a parable for training since it describes a difficulty about Zazen or meditation and transforming it into life. I tell this because I've met many people who were self styled meditation experts, but who could not convert that 'skill' of sitting to walking, eating, sleeping, everyday. I've emphasized this gap many times, but I'll bring it up here again. Whether you think you are trying to attain Buddhahood, Samadhi or relaxation, whatever name you find to put to it, the point is the same. Here is the koan;
Baso stayed at Denpo-in on the same mountain, doing nothing but zazen day an night. One day master Nangaku asked Baso, 'Reverend Sir, what are you doing here?" "I am doing zazen" answered Baso. "What are you going to accomplish by doing zazen?" asked Nangaku. Baso replied "I am only trying to be a Buddha". Hearing that Nangaku walked away wihout a word and picked up a piece of brick in the garden, and started to polish it with a grinding stone in front of his hut. Baso asked wondering"what are trying to accomplish by polishing a brick?" "I am trying to make a mirror by polishing this brick", replied Nangaku. Baso asked again "can a piece of brick be made into a mirror by polishing?" Nangaku retorted, "Can one become a Buddha by doing zazen?"Baso went on to ask, what should I do then?" Nangaku said, "It is like putting a cart to an ox. When the cart does not move, which is better, to beat the cart or the ox?"Baso was unable to answer. Nangaku then kindly explained to him, "You practice zazen and try become Buddha by sitting. If you want to learn hot to do zazen, know that zazen is not in sitting or lying. If you want to become a Buddha by sitting, know that Buddha has no fixed form. Never discriminate in living in the Dharma of nonattachment. If you try to become a Buddha sitting, you are killing Buddha. If you attach to the form of sitting, you can never attain Buddhahood".
Who are you? You can just do zazen, you can do a lot of zazen, but if you just try to use it like an aspirin you never get anywhere. Aspirin is OK, it's medicine when you are sick, but it's not your life.
You have to address your life. Take responsibility, not just crawl into your zafu every time it gets heavy. Of course life is heavy.
So you spend the first part of your life finding yourself. What's enlightenment? It's realizing your situation, after that you roll up your sleeves and get on with it. You spend the second part of your life showing us who you are.
Then your zazen transforms, it's no longer about taking an aspirin for your pain.
This is a deep situation of course, too deep to go into here. But suffice to say training in Zen is about breaking free of attachment to forms (and ideas), maturing your eye to see what is around you, '...Buddha has no fixed form...'
We know that Baso was a scholar who studied the Pali and Chinese scriptures, a learned expert, just like many Baso is you trying to make that final step into self realization and demonstration, maturation.
* The Gateless Barrier Zen Comments on the Mumonkan by Zenkei Shibayama. This book is the current training standard text in Rinzai training centres.
**Baso often transliterated Matsu or Mazu in Chinese and Nangaku from Huairang, in Chinese.