Abstract

The world is a unification of matter, energy and information. Subjectivity information is such information that subject receives, deals with and expresses. Subjectivity information can be classified to two categories by form: image and symbol. On the basis of ontology of ‘matter, energy and information——triunity’, this paper presents the definitions of symbol and image, points out the origin of them and brings forward the mechanism that men cognize symbols. Also, the paper classifies symbols in two ways: In one way, according to essence, origin and function, symbols can be classified to three categories: image symbols, appellation symbols and digit symbols. In the other way, symbols can be classified to two categories: static symbols and dynamic symbols, according to the carriers. Moreover, the author discussed the respective advantages and characteristics of image and symbol, especially presented four important characteristics of symbols: 1) be derived from definitions; 2) rely on manifold brain activities; 3) discretization; 4) meaning congruence. In the end, the author pointed out the epoch-making significance of symbols in the process that animals evolved into men.