COMMA, among grammarians, a point or character marked thus (,), serving to denote a short stop, and to divide the members of a period. Different authors define and use it differently. According to Buffier, the comma serves to distinguish the members of a period, in each of which is a verb and the nominative case of the verb: thus, "That so many people are pleased with trifles, is owing to a weakness of mind, which makes them love things easy to be comprehended." Besides this, the comma is used to distinguish, in the same member of a period, several nouns substantive or nouns adjective, or verbs not united by a conjunction: thus, "Virtue, wit, knowledge, are the chief advantages of a man;" or, "A man never becomes learned without studying constantly, methodically, with gusto, application," &c. If such words are united in the same phrase with a conjunction, the comma is omitted: thus, "The imagination and the judgment do not always agree."
The ingenious author of the tract De Ratione Interpungendi, printed with Vossius's Element. Rhetor. London, 1734, lays down the use of a comma to be, to distinguish the simple members of a period or sentence; that is, such as only consist of one subject and one definite verb. But this rule does not hold throughout; the same author instancing many particular cases not yet included in it, where the comma is advisable.
It is a general rule that a comma ought not to come
between a nominative and a verb, or an adjective and substantive, when these are not otherwise disjoined: thus, in the sentence, God ruleth with infinite wisdom, a comma between God and ruleth, or between infinite and wisdom, would be absurd. But to this exceptions may occur; as when not a single word, but a sentence, happens to be the nominative; thus, in the example first above given, where the sentence that so many people are pleased with trifles, forms the nominative to the verb is, a comma at trifles is proper, both for the sake of perspicuity, and as coinciding with a slight natural pause. See PUNCTUATION.