Abstract:

Halliday divides grammatical metaphors into ideational grammatical metaphor and interpersonal grammatical metaphor on the basis of its functions. Yet many scholars at home and abroad have argued that there do exist the third kind-textual metaphor. Exemplified by the commencement speeches of Harvard University from 2007-2012, the author will present the application of textual metaphors and illustrate how its five types: thematic equatives, predicated theme, thematic comment sentence, passive sentence and compound noun phrase, are used in the samples.

Key words: Grammatical Metaphor; Textual Metaphor; Commencement Speeches

摘要：

韩礼德从功能上将语法隐喻划分为概念语法隐喻和人际语法隐喻。然而许多国内外学者提出有第三种隐喻的存在，语篇隐喻。作者以2007-2012年哈佛毕业演讲为例，探讨其中五种语篇隐喻，即主位同等结构，谓化主位结构，主位化评论句，被动语态句和名词复合词组在所选演讲语篇中的运用。

关键词：语法隐喻；语篇隐喻；毕业演讲

1. Introduction
When we talk about grammatical metaphor, Halliday is the first person that usually comes to mind. In his early years when he studied on the nature of the language, he came up with an idea that metaphor exists not only at lexical level, but also at syntactic level. In other words， grammatical metaphor is the transformation of syntactic form or grammatical category. Grammatical metaphor is a relative phenomenon to the lexical metaphor. The former refers to the same signified, different signifier while the latter refers to the same signifier, different signified. Furthermore, on the basis of its functions, Halliday divides grammatical metaphor mainly into two parts, ideational grammatical metaphor and interpersonal grammatical metaphor. The former pattern of manifestation is in the process of using noun form to express what verb and adjective can express and the latter’s main pattern of manifestation is in the process of using clause instead of adverb which can express interpersonal meanings in the form of propositions. So, “metaphor” mentioned in this paper is no more a rhetorical device than the transformation of different grammatical categories.
The research of metaphors can be traced back to two thousand years. Many scholars, domestic and foreign, also have studied on metaphor from different aspects. What they’ve found and established covers its existence form, universality and importance. This paper intends to analyze the characteristics of metaphorical language in different English speeches by studying Commencement Speeches of Harvard University from 2007-2012. Consequently, we could explore the functions and significance of using grammatical metaphors in the aspect conveying speakers’ intentions.