be guided by their decisions, it is proper for us to consider what degree of certainty there is in the rule, and what difference or concurrence there is among them:  for, the teaching of any other than the best opinions, is not the teaching of science, come from what quarter it may.  On the question respecting the objective case of nouns, Murray and Webster changed sides with each other; and that, long after they first appeared as grammarians.  Nor was this the only, or the most important instance, in which the different editions of the works of these two gentlemen, present them in opposition, both to themselves and to each other.  “What cases are there in English?  The nominative, which usually stands before a verb; as, the boy writes:  The possessive, which takes an s with a comma, and denotes property; as, John’s hat:  The objective, which follows a verb or preposition; as, he honors virtue, or it is an honor to him.”—­Webster’s Plain and Comp.  Gram., Sixth Edition, 1800, p. 9.  “But for convenience, the two positions of nouns, one before, the other after the verb, are called cases.  There are then three cases, the nominative, possessive, and objective.”—­Webster’s Rudiments of Gram., 1811, p. 12.  “In English therefore names have two cases only, the nominative or simple name, and the possessive.”—­ Webster’s Philosoph.  Gram., 1807, p. 32:  also his Improved Gram., 1831, p. 24.

OBS. 9.—­Murray altered his opinion after the tenth or eleventh edition of his duodecimo Grammar.  His instructions stand thus:  “In English, substantives have but two cases, the nominative, and [the] possessive or genitive.”—­Murray’s Gram. 12mo, Second Edition, 1796, p. 35.  “For the assertion, that there are in English but two cases of nouns, and three of pronouns, we have the authority of Lowth, Johnson, Priestley, &c. names which are sufficient to decide this point.”—­Ib., p. 36.  “In English, substantives have three cases, the nominative, the possessive, and the objective.”—­Murray’s Gram., 12mo, Twenty-third Edition, 1816, p. 44.  “The author of this work long doubted the propriety of assigning to English substantives an objective case:  but a renewed critical examination of the subject; an examination to which he was prompted by the extensive and increasing demand for the grammar, has produced in his mind a full persuasion, that the nouns of our language are entitled to this comprehensive objective case.”—­Ib., p. 46.  If there is any credit in changing one’s opinions, it is, doubtless, in changing them for the better; but, of all authors, a grammarian has the most need critically to examine his subject before he goes to the printer.  “This case was adopted in the twelfth edition of the Grammar.”—­Murray’s Exercises, 12mo, N. Y., 1818, p. viii.