Comparison does not refer to an implicit norm. Some other object is used for the purpose of comparison and the graded object is measured against it. Thus, This tree is larger can only be understood if we can answer the question Larger than what? The answer is not ‘the norm for trees’ but some other object, possibly, but not necessarily, another tree. The missing information may be given immediately after the comparative expression: This tree is larger than the one in that field. Or it may be discoverable only by back reference. We must note that saying that a tree is larger than another tree, or larger than something that is not a tree, does not mean that it is a large tree; it could be quite small as trees in general go. In general there are three types of comparison. We can say that something has more of a quality (the superior relation), or less of a quality (the inferior relation), or just as much of a quality (the equal relation): heavier/more interesting (than…) (superior); less heavy/less interesting (than…) (inferior); as heavy/as interesting (as…) (equal). There is another kind of the ‘equal’ comparative relation. It is rather like the ‘as…as’ kind that we find in This document is as long as that one. But this time, instead of comparing the length of one document with that of another, we compare it with the length that would be required for some result to follow. This document is so long that I haven’t time to read it; i.e. its length is greater
than the maximum length that would allow me to have time to read it. The same meaning can be expressed with the words too and enough used as modifiers to the adjective: The mountain is so high that the top is in the clouds The mountain is high enough for the top to be in the clouds The mountain is so high that nobody has climbed it The mountain is too high for anybody to have climbed it A curious thing about the word enough is that it comes after the adjectival head instead of before it, while too comes in the usual position: too high, but high enough. The part of the adjective phrase that comes after the head is quite complex in structure, and the structure varies in different types of expression. Beyond showing the overall principle of structure for such phrases (Figure 19) we shall not go into this matter further. The adjective phrases in Figure 19 have the adjective as the head and the other elements in the structure
are pre-modifiers or post-modifiers.