So that is why, in Zen sutras are not necessary, Sutras only talk about mind and explain mind:
"Everything is created by mind alone."
"The Buddha taught all Dharmas in order to save all minds."
"All Dharmas come from complete stillness."
These words are very wonderful medicine for our thinking-minds.
All sutras and Dharmas are wonderful pictures for showing a hungry man what a banana looks like.
Only eating the banana will take away his suffering; the pictures cannot do this.