yugen

It means 'what lies beneath the surface': the subtle, as opposed to the obvious; the hint, as opposed to the statement. It is applied to the natural grace of a boy's movements, to the gentle restraint of a noble man's speech and bearing. 'When notes fall sweetly and flutter delicately to the ear' that is the yugen of music. The symbol of yugen is 'a white bird with a flower in its beak.' 'To watch the sun sink behind a flower-clad hill, to wander on and on in a huge forest with no thought of return, to stand upon the shore and gaze after a boat that goes hid by far-off islands, to ponder on the journey of wild geese seen and lost among the clouds [Zeami Motokiyo, tr. Whaley]' -- such are the gates of yugen.

-- Arthur Whaley More Translations from the Chinese