Aesthetic thought: Aesthetic thought is the product of the development of human aesthetic practice and artistic practice to a certain historical stage, and it is a philosophical summary of human aesthetic practice and artistic practice. The early aesthetic thoughts of mankind are scattered in a large number of ancient works, such as literature, painting theory, calligraphy theory, music theory, passbook science, history and so on. None of these have a systematic theory. Systematic aesthetic thoughts are often condensed and crystallized into some aesthetic categories and propositions, which are the basis of aesthetics, but not aesthetics as an independent discipline.

Aesthetic subject: aesthetic subject refers to the subject in aesthetic activities, and is the sender and undertaker of aesthetic activities. In aesthetic activities, it forms an objective relationship with aesthetic objects. Aesthetic subject has inherent aesthetic demand and pursuit, which is the motive force of aesthetic activities and plays an active leading role in aesthetic activities. So it can also be said.

The aesthetic subject is a concrete person. The aesthetic subject also has the corresponding aesthetic ability and aesthetic standard, which is the guarantee for the development of aesthetic activities and the necessary evaluation standard for aesthetic activities.

Principles of Aesthetics is an aesthetic research work created by Italian writer Croce, which was published by Shanghai People's Publishing House in April 2007. This book mainly tells the position of aesthetics in the whole philosophy, and the differences and connections between aesthetic activities and other spiritual activities.