OBS. 15. If a clause beginning with as, because, if, wherever, how, lest, than, that, when, where, whether, while, why, or any {p106} adverb of time, place, or manner, follows a clause with which it is closely connected in sense, it is not set off by a comma: “He went away when the boat left.” “We love him because he first loved us.” “He will pay if he is able.” “Tell me whether you will return.”
OBS. 16. An infinitive phrase closely connected with what it modifies, should not be set off by a comma; as, “We use language to express our thoughts.” “Nouns do not vary their endings to denote certain cases.” But if the infinitive phrase is preceded by in order, or if it is remote from what it modifies, it should be set off by a comma. “He collected a great many young elms from various parts of England, to adorn his grounds.” “If dissimulation is ever to be pardoned, it is that which men have recourse to, in order to obtain situations which will enlarge their sphere of general usefulness.”
21. A word or phrase used in apposition, to explicate or illustrate a previous word or phrase, should be set off by commas; but if the words in apposition constitute a single phrase or a proper name, they should not be separated.
a. Comma required.
Johnson, that mighty Caliban of literature, is held up to view in the pages of Boswell.
The alligator, or cayman, is found in the Orinoco.
Paul, the apostle of the Gentiles, was eminent for his zeal and knowledge.
If the position of the terms in apposition is reversed, commas are required.
The apostle of the Gentiles, Paul, was eminent for his zeal and knowledge.
That old last century poet, Crowley, sings thus.