[212] The _principle_ of Bacon’s prerogative instances, and perhaps in some cases a very analogous application of them, appear to hold in our inquiries into historical evidence. The fact sought to be ascertained in the one subject corresponds to the physical law in the other. The testimonies, as we, though rather laxly, call them, or passages in books from which we infer the fact, correspond to the observations or experiments from which we deduce the law. The necessity of a sufficient induction by searching for all proof that may bear on the question, is as manifest in one case as in the other. The exclusion of precarious and inconclusive evidence is alike indispensable in both. The selection of prerogative instances, or such as carry with them satisfactory conviction, requires the same sort of inventive and reasoning powers. It is easy to illustrate this by examples. Thus, in the controversy concerning the Icon Basilike, the admission of Gauden’s claim by Lord Clarendon is in the nature of a _prerogative instance_; it renders the supposition of the falsehood of that claim highly improbable. But the many second hand and hearsay testimonies which may be alleged on the other side, to prove that the book was written by King Charles, are not prerogative instances, because their falsehood will be found to involve very little improbability. So, in a different controversy, the silence of some of the fathers as to the text, commonly called, of the three heavenly witnesses, even while expounding the context of the passage, is a _quasi-prerogative instance_; a decisive proof that they did not know it, or did not believe it genuine; because if they did, no motive can be conceived for the omission. But the silence of Laurentius Valla as to its absence from the manuscripts on which he commented, is no prerogative instance to prove that it was contained in them; because it is easy to perceive that he might have motives for saying nothing; and, though the negative argument, as it is called, or inference that a fact is not true, because such and such persons have not mentioned it, is, taken generally, weaker than positive testimony, it will frequently supply prerogative instances where the latter does not. Launoy, in a little treatise, De Auctoritate Negantis Argumenti, which displays more plain sense than ingenuity or philosophy, lays it down that a fact of a public nature, which is not mentioned by any writer within 200 years of the time, supposing, of course, that there is extant a competent number of writers who would naturally have mentioned it, is not to be believed. The period seems rather arbitrary, and was possibly so considered by himself; but the general principle is of the highest importance in historical criticism.