Systematicity in metaphor, which is one of the dominant features of conceptual metaphor, according to its definition, is composed of the coherence of metaphorical concepts and the incompleteness of mappings. However, as for the life metahpr in William Shakespeare’s four great tragedies, it is discovered that the coherence theory cannot fully explain the metaphor system. The feature of metaphor’s systematicity more follows the basic principles of Basic System Theory, i.e. hierarchy, relevance, dynamic openness and functionality. While on studies of conceptual metaphors, the metaphor and its expression need to be given more focus and be studied from a systematical and comprehensive view. Therefore, it is of great importance to focus on the elements and sub-systems in the metaphor system and to explore the nature of conceptual metaphor.