It is necessary, therefore, that before an author be charged with plagiarism, one of the most reproachful, though, perhaps, not the most atrocious of literary crimes, the subject on which he treats should be carefully considered. We do not wonder, that historians, relating the same facts, agree in their narration; or that authors, delivering the elements of science, advance the same theorems, and lay down the same definitions: yet it is not wholly without use to mankind, that books are multiplied, and that different authors lay out their labours on the same subject; for there will always be some reason why one should on particular occasions, or to particular persons, be preferable to another; some will be clear where others are obscure, some will please by their style and others by their method, some by their embellishments and others by their simplicity, some by closeness and others by diffusion. The same indulgence is to be shown to the writers of morality: right and wrong are immutable; and those, therefore, who teach us to distinguish them, if they all teach us right, must agree with one another. The relations of social life, and the duties resulting from them, must be the same at all times and in all nations: some petty differences may be, indeed, produced, by forms of government or arbitrary customs; but the general doctrine can receive no alteration. Yet it is not to be desired, that morality should be considered as interdicted to all future writers: men will always be tempted to deviate from their duty, and will, therefore, always want a monitor to recall them; and a new book often seizes the attention of the publick, without any other claim than that it is new. There is likewise in composition, as in other things, a perpetual vicissitude of fashion; and truth is recommended at one time to regard, by appearances which at another would expose it to neglect; the author, therefore, who has judgment to discern the taste of his contemporaries, and skill to gratify it, will have always an opportunity to deserve well of mankind, by conveying instruction to them in a grateful vehicle. There are likewise many modes of composition, by which a moralist may deserve the name of an original writer: he may familiarize his system by dialogues after the manner of the ancients, or subtilize it into a series of syllogistick arguments: he may enforce his doctrine by seriousness and solemnity, or enliven it by sprightliness and gaiety: he may deliver his sentiments in naked precepts, or illustrate them by historical examples: he may detain the studious by the artful concatenation of a continued discourse, or relieve the busy by short strictures, and unconnected essays.