Where the mood of the moment is solitary and quiet it is called sabi. When the artist is feeling depressed or sad, and in this peculiar emptiness of feeling catches a glimpse of something rather ordinary and unpretentious in its incredible “suchness,” the mood is called wabi. When the moment evokes a more intense, nostalgic sadness, connected with autumn and the vanishing away of the world, it is called aware. And when the vision is the sudden perception of something mysterious and strange, hinting at an unknown never to be discovered, the mood is called yugen. These extremely untranslatable Japanese words denote the four basic moods of furyu, that is, of the general atmosphere of Zen “taste” in its perception of the aimless moments of life.
— The Way of Zen by Alan Watts (Part 2, Chapter 4)
