One the main features of the concept of Yugen is ineffability. The obvious is replaced by the hidden. The ultimate reality, concealed behind the object, cannot be precisely defined. Profound feelings cannot be portrayed on the face or expressed directly. One can only hint at them, let others know of their existence, so that the viewer or reader may sense them within themselves. Yugen reflectsincompletennes, the mystery of becoming, as well as blurred boundaries. The inability to focus on the subject and form the complete understanding of it. In literature, these states are often conveyed trough images of sunsets, dawn and dusk, starry skies, moonlight, fog, the fleeting smoke of a campfire, and so on

Hope and believe,
trusting only in one thing as your support -
the vow we have made.
And this sorrowful world is but a fleeting dream,
nothing more.

Fujiwara - no Teika (Sadaie)

- Wikipedia -