This term refers to an inner experience one gains under special circumstances. When the mind is so relaxed and peaceful, it allows one to develop an intimate appreciation and understanding of beauty and then express it in a poem. The beauty of the poem thus inspired transcends words and creates an intense aesthetic experience. Subtle insight enables the reader to appreciate the essence and lasting beauty of a poem by creating a spontaneous experience so engrossing that one becomes oblivious to both himself and the outside world. According to Buddhist, Daoist, and Metaphysical principles, “subtle” refers to the minute and profound nature of thinking, whereas “insight” is an intensely personal experience derived not from logical reasoning. Chan Buddhism promotes meditation as a way to return to the mind’s original tranquility and thus achieve a clear and simple state of mind. Such a state of mind comes from literary and artistic experience. In Canglang’s Criticism of Poetry, literary critic Yan Yu （？-1264）of the Southern Song Dynasty dealt extensively with the function and features of subtle insight in poetry writing by drawing on Chan philosophy. This book is the first one to apply Chan terms to critical writing on poetry and has thus gained great influence. The concept of subtle insight has also influenced traditional painting and calligraphy in China.

By concentrating one’s mind and freeing one’s thoughts, one can reach such a fascinating state in appreciating the beauty of nature as to become oblivious to the outside world and one’s own self, totally free from the constraints of physical forms and limitations of knowledge.

(Zhang Yanyuan: Famous Paintings Through History)

Generally speaking, the most important principle of meditation is to achieve subtle insight, and this is the most important principle underlying poetry writing as well. For example, while Meng Haoran is no equal to Han Yu in terms of knowledge and talent, his poems surpass those of Han Yu because he is able to create subtle insight. (Yan Yu: Canglang’s Criticism of Poetry)