Metaphorical sentences and nonmetaphorical sentences are closely related in meaning and structure. Semantically, metaphorical sentences and their corresponding nonmetaphorical sentences are supposed to be the same. The relationship between them is a logical one, that is, a synonymous one. Therefore, metaphorical sentences are supposed to express the meaning of nonmetaphorical sentences. However, one cannot reasonably expect a metaphorical sentence and a nonmetaphorical sentence to be totally synonymous. "The selection of metaphor is itself a meaningful choice, and the particular metaphor selected adds further semantic features." (Halliday, 1994: 342) The congruent and the incongruent versions, in Halliday's term, are only "systematically related in meaning, and therefore synonymous in certain respects. In the following example, (b) is the incongruent form and (c) is the congruent form. They are understood as synonymous to some extent. Actually, they are different. Firstly, the processes used are different. One is in a behavioural process while the other is in a sensuous process. Secondly, the information structure is different. The theme is a sudden impulse in (b), but it is I in (c). Finally, (c) is a stative statement while (b) is a dynamic description. All the factors above show that the two sentences are somewhat different in meaning.

(1) 

(b) A sudden impulse seized me to visit Thrushcross.

(c) I suddenly wanted to visit Thrushcross.

Structurally, metaphorical sentences and their corresponding nonmetaphorical sentences are also supposed to be the same. The relationship between them is an embryological one. So the author deems them to be of the same sentence pattern. This is true, indeed, because metaphorical sentences are usually modeled on nonmetaphorical sentences in structure. In the following example, (a) is a nonmetaphorical sentence and (b) is a metaphorical sentence since (b) does not have the normal Behaver or the normal Patient that the process usually requires. (b) is modeled on (a) in structure.

(2) 

(a) Tom gave Mary a book.

(b) The film gave us much pleasure.

However, generally speaking, metaphorical sentences and their corresponding nonmetaphorical sentences cannot be the same both in structure and in meaning. If a metaphorical sentence and a nonmetaphorical sentence are the same in structure, they are usually different in meaning, as is shown in (2). On the contrary, if a metaphorical sentence and a nonmetaphorical sentence are the same (to some extent) in meaning, they are usually different in structure, which has been shown by (1). But of course there are exceptions. When a metaphorical sentence and a corresponding nonmetaphorical sentence are both embodied in SVC sentence pattern, they are fundamentally the same both in structure and in meaning. For example: