Wakuan saw a picture of bearded Bodhidharma and complaint
"Why has the barbarian from the West no beard?"
(The Koan-answer is the picture's caption!)
Stroke your beard
An explanation of the Koan answer
The master mentioned, the question, the legend of Bodhidharma and his pictures have nothing to do with the Koan.
They are just ornament, part of an old stories everybody knows. Nothing real.
Whether Bodhidharma actually had a beard or not is, at the end, just the same. The one "real thing" in this Koan is the beard.
Unconsciously stroking your (existing or non existing) beard shows you got the Koan.
The background story of this Koan
In early, classical China all non-Chinese, sometimes even Chinese people, living at the southwest borders of China were called "barbarians". This translation of the Chinese word "hu" comes from ancient Greece. They called everyone who lived in neighbouring countries barbarians.
Bodhidharma, it was believed, was an Indian who brought Zen to China. He was often just called "the barbarian" and depicted with the big beard all barbarians have.
Everybody knew about that, and all pictures of Bodhidharma showed him with a big beard.
Wakuan's question therefore denies the obvious, it's a bit ironic.
Traditional Commentaries and .... Poems (Gata)
If you want to study Zen, you must study it with your heart. When you attain realization, it must be true realization.
You yourself must have the face of the great Bodhidharma to see him. Just one such glimpse will be enough.
But if you say you met him, you never saw him at all.
Meeting must be real meeting, awakening must be real awakening. (Or: Meeting the beard is real meeting, realizing the beard is real realization.)
Those who would encounter the barbarian one must see his beard intimately first hand one time and only then they get it. But, if you speak about being intimate, you have already become two.
One should not discuss a dream
In front of a simpleton.
Why has Bodhidharma no beard?
What an absurd question!
Before the face of a foolish person
You shouldn’t tell your dream,
“Mr. Barbarian is beardless”
Is mouthing wakefulness.