Daniel G. Brinton,
The Philosophic Grammar of American Languages…
“ I choose those of America as best suited to such a purpose, and select the Verb as the most important part of speech, and the central point of every language. Without entering into an analysis of the different parts of the verb, I shall confine myself to that which constitutes its peculiar verbal character—the union of the subject and predicate of the sentence by means of the notion of Being. This alone forms the essence of the verb; all other relations, as of persons, tenses, modes and classes, are merely secondary properties. ”
