22-1. The woods may disappear, but the spirit of them never will now.
Expanding the above, to emphasize the relations, but still maintaining the sense of No. 22, we get the following:
22-2. The woods may disappear, for they are material and will decay; but the spirit of them never will now, for it has been felt by a poet and we can feel forever what he felt.
In No. 22-2 we added a commonplace modifier to the first statement in the sentence, in order to exhibit more clearly the similar relation between two like groups in the second part of the sentence, which take a semicolon in the quoted sentence (No. 22).
Punctuated so as to show the real sense relations, the sentence reads as follows:
22-3. The woods may disappear: but the spirit of them never will now; for it has been felt by a poet, and we can feel forever what he felt.
A thorough comprehension of the groupings in these sentences, which is based upon sense relations, will illuminate the punctuation already discussed. It will also explain some apparent, if not real, inconsistencies that are inevitable in dealing with marks to express indefinite degrees of relation.
Sentence 1 is composed of two clauses connected by a conjunction, as is also Sentence 22-1. The liability to error in grouping Sentence 1 may be sufficient to require a semicolon; but the grouping in Sentence 22-1 is so unmistakable that a comma is sufficient to give notice of a change in the direction of the thought. In Sentence 21 the semicolon gives notice of a grouping which does not follow. In Sentence 22 the grouping by punctuation does not follow the meaning of the language, and is therefore wrong.
Wrong grouping is perhaps most common in sentences containing groups requiring coördinate conjunctions, such as “and” and “but.” Quite often such sentences cannot be so punctuated as to show the correct grouping by the marks. The following sentence is an example:
23. The Society has expelled two of its members for unprofessional conduct, and has investigated complaints against two other members, but it has been unable to obtain enough evidence to convict them.