“The meaning of the phrase mono no aware is complex and has changed over time, but it basically refers to a “pathos” (aware) of “things” (mono), deriving from their transience. In the classic anthology of Japanese poetry from the eighth century, Manyōshū, the feeling of aware is typically triggered by the plaintive calls of birds or other animals. It also plays a major role in the world’s first novel, Murasaki Shikibu’s Genji monogatari (The Tale of Genji), from the early eleventh century. The somewhat later Heike monogatari (The Tale of the Heike Clan) begins with these famous lines, which clearly show impermanence as the basis for the feeling of mono no aware:
The sound of the Gion shōja bells echoes the impermanence of all things; the color of the sōla flowers reveals the truth that the prosperous must decline. The proud do not endure, they are like a dream on a spring night; the mighty fall at last, they are as dust before the wind.”
—“Japanese Aesthetics,” The Stanford Encyclopedia of Philosophy