This is a famous statement made by Zhuangzi (369?-286 BC)on how beauty is relative. Originally it meant there was no difference between a beauty and an ugly person, because they both came from and reflected Dao. The character 厉 (lai) meant 癞 (lai, covered in scabs) in ancient Chinese. Whether a person is beautiful or ugly is but a subjective perspective in the mind of the beholder. Besides, beauty can turn into ugliness, and vice versa. Zhuangzi, from the perspective of the origin of all things, stressed that beauty and ugliness are both in accord with Dao and are inherently the same. This idea has encouraged later literary critics to look at all things, including literary works, from the perspective that opposite things complement each other.

In the light of dao, a small blade of grass or a tall pillar, someone as ugly as a favus patient or someone as beautiful as Lady Xishi, as well as crafty and strange things, are all the same. (Zhuangzi)

The grand appearance is an external manifestation of dao, while the true vitality permeates itself internally. Reverting to a tranquil void, one may gain fullness and amass inner strength, and he will produce powerful works. (Sikong Tu: Twenty-Four Styles of Poetry)