Grammar books often use examples that we never see in real life. This Appendix uses examples from books to illustrate some additional points. As my comments show, it is not always clear how to classify things, but what matters more is how well the logic of the sentence works for the reader.
The basic logic relates to verbs and their subjects – which may be nouns, pronouns or their equivalent. Adverbs and adjectives say something else about verbs and nouns.
A strong message in this book is that a sentence should contain a verb. That is the main thing to remember: if your sentence sounds odd, is that because a verb or part of a verb is missing?
What counts as a verb? The expression 'a verb is a doing word' may not be very helpful, as sometimes that doing is just existing or even just helping to complete other verbs. It is also possible to see action in bits of verbs that are not complete in themselves.
These and other issues are illustrated in the following passage, where the finite (complete) verbs are italicized.
He was systematic, but to say he thought and acted like a machine would be
to misunderstand the nature of his thought. It was not like pistons and
wheels and gears all moving at once, massive and co-ordinated. The image
of a laser beam comes to mind instead; a single pencil of light of such
terrific energy in such extreme concentration it can be shot at the moon
and its reflection [can be] seen back on earth. Phaedrus did not try to use his
brilliance for general illumination. He sought one specific distant target
and aimed for it and hit it. And that was all. General illumination of that
target he hit now seems to be left for me.
(Pirsig 1974: 80)
This passage illustrates a number of points I want to add about verbs.