2.3.2 Classifications of Conceptual Metaphor
In Metaphors We Live By Lakoff pides conceptual metaphor into three kinds. They are orientational metaphor, ontological metaphor and structural metaphor, which are all based on the experimentalist synthesis.
3.2.1 Orientational Metaphor.

2.3.2.1 Orientation Metaphor
Orientational metaphor or spatialization metaphor is related to our perception of space. It is an interesting question where the first concept comes from. Lakoff and Johnson believe that the initial concept derives from spatial orientation that comes from physical basis (Lakoff ﹠Johnson 1980: 14 ff). Orientational metaphor gives those abstract concepts a spatial orientation, helping people perceive their experience and the outside world via concepts such as up-down, in-out, front-back and so on. On ground of it people can understand abstract concepts like "happiness", "health", "life" and so on. Thus orientational metaphor like HAPPY IS UP. SAD IS DOWN, HEALTH IS UP, AILMENT IS DOWN, LIVE IS UP, DEATH IS DOWN are formed. And why UP stands for good and DOWN for bad? This originates from the basic experience (Feng Xiaohu 2004: 116). At the very beginning when language occurred, "up" often means "good" for our ancestors, because it is always safe for ape-man living in high trees; high and dry places are ideal accommodation for living. So "good" had become the preferred meaning of "up" (Feng Xiaohu 2004: 117).

2.3.2.2 Ontological Metaphor
Ontological metaphor regards feelings, emotions, occurrence, ideas, etc. as substances and entities. when exploring the world and summing up experience, it is not enough using orientational metaphor only. Due to the lack of knowledge of the world, people understood various phenomenon hardly, and nothing but their own body was the most familiar thing to them. So they made use of parts of their own body to explain the world. And our body becomes the main source of ontological metaphor. Based on ontological metaphor, people identify their experience of exploring the world as entities or substances, which they can classify, integrate and thus systematize them (Feng Xiaohu 2004: 117). For example, people view their bodies as containers, so gradually they utilize in-out concept to perceive the world. Thus they say swim in the water, go through the frost, step into a room, etc.
 
2.3.2.3 Structural Metaphor
According to Lakoff and Johnson, structural metaphor is "cases where one concept is metaphorically structured in terms of another" (Lakoff ﹠Johnson 1980: 14). The source domain offers the target domain a structure, by which means speakers can perceive and understand the target domain via the structure of the source domain. Structural metaphors allow us to use one highly structured and clearly delineated concept to structure another (Lakoff ＆ Johnson, 1980: 15). Take LIFE IS JOURNEY as an example. In this case, the concept of LIFE is structured in accordance with the structure of JOURNEY. We understand life on the basis of journey as they are both a kind of process consisting of a beginning, an ending, time duration, destination and so on. What the difference is the concept of journey is more concrete than that of life. People can perceive and understand the meaning of journey by the structure of itself, rather than other metaphors people invent. Thus the source domain plays a very important role in structural metaphor. And the structural metaphor not only helps us to perceive the abstract concept, but also the structure of it.

2.3.3 Functions of Conceptual Metaphor
Cognitive linguistics overthrow the conventional viewpoint of metaphor and point out that metaphor is a very important tool for cognition and communication (Lakoff ﹠Johnson 1980: 16). It not only helps people understand and experience the world, but also shapes the conceptual system of people.

2.3.3.1 Three Basic Functions of Conceptual Metaphor 美剧《复仇》的语篇分析(4):http://www.751com.cn/yingyu/lunwen_9177.html