Edward Gibbon, A Vindication (§ 12):

After a short description of the unworthy conduct of those Apostates who, in a time of persecution, deserted the Faith of Christ, I produced the evidence of a Pagan Proconsul, and of two Christian Bishops, Pliny, Dionysius of Alexandria, and Cyprian. And here the unforgiving Critic remarks,

“That Pliny has not particularized that difference of conduct (in the different Apostates) which Mr. Gibbon here describes: yet his name stands at the head of those Authors whom he has cited on the occasion. It is allowed indeed that this distinction is made by the other Authors; but as Pliny, the first referred to by Mr. Gibbon, gives him no cause or reason to use them,” (I cannot help Mr. Davis’s bad English) “it is certainly very reprehensible in our Author, thus to confound their testimony, and to make a needless and improper reference.”

A criticism of this sort can only tend to expose Mr. Davis’s total ignorance of historical composition. The Writer who aspires to the name of Historian, is obliged to consult a variety of original testimonies, each of which, taken separately, is perhaps imperfect and partial. By a judicious re-union and arrangement of these dispersed materials, he endeavours to form a consistent and interesting narrative. Nothing ought to be inserted which is not proved by some of the witnesses; but their evidence must be so intimately blended together, that as it is unreasonable to expect that each of them should vouch for the whole, so it would be impossible to define the boundaries of their respective property. Neither Pliny, nor Dionysius, nor Cyprian, mention all the circumstances and distinctions of the conduct of the Christian Apostates; but if any of them was withdrawn, the account which I have given would, in some instance, be defective.

Thus much I thought necessary to say, as several of the subsequent misrepresentations of Orosius, of Bayle, of Fabricius, of Gregory of Tours, etc, which provoked the fury of Mr. Davis, are derived only from the ignorance of this common historical principle.

Another class of Misrepresentations, which my Adversary urges with the same degree of vehemence (See in particular those of Justin, Diodorus Siculus, and even Tacitus), requires the support of another principle, which has not yet been introduced into the art of criticism; that when a modern historian appeals to the authority of the ancients for the truth of any particular fact; he makes himself answerable, I know not to what extent, for all the circumjacent errors or inconsistencies of the authors whom he has quoted.

Edward Gibbon, The Decline and Fall of the Roman Empire, Chp. V:

“The power of the sword is more sensibly felt in an extensive monarchy, than in a small community. It has been calculated by the ablest politicians, that no state, without being soon exhausted, can maintain above the hundredth part of its members in arms and idleness. But although this relative proportion may be uniform, the influence of the army over the rest of the society will vary according to the degree of its positive strength. The advantages of military science and discipline cannot be exerted, unless a proper number of soldiers are united into one body, and actuated by one soul. With a handful of men, such a union would be ineffectual; with an unwieldy host, it would be impracticable; and the powers of the machine would be alike destroyed by the extreme minuteness or the excessive weight of its springs. To illustrate this observation, we need only reflect, that there is no superiority of natural strength, artificial weapons, or acquired skill, which could enable one man to keep in constant subjection one hundred of his fellow-creatures: the tyrant of a single town, or a small district, would soon discover that a hundred armed followers were a weak defence against ten thousand peasants or citizens; but a hundred thousand well-disciplined soldiers will command, with despotic sway, ten millions of subjects; and a body of ten or fifteen thousand guards will strike terror into the most numerous populace that ever crowded the streets of an immense capital. The Praetorian bands, whose licentious fury was the first symptom and cause of the decline of the Roman empire, scarcely amounted to the last-mentioned number. They derived their institution from Augustus. That crafty tyrant, sensible that laws might color, but that arms alone could maintain, his usurped dominion, had gradually formed this powerful body of guards, in constant readiness to protect his person, to awe the senate, and either to prevent or to crush the first motions of rebellion. He distinguished these favored troops by a double pay and superior privileges; but, as their formidable aspect would at once have alarmed and irritated the Roman people, three cohorts only were stationed in the capital, whilst the remainder was dispersed in the adjacent towns of Italy.  But after fifty years of peace and servitude, Tiberius ventured on a decisive measure, which forever rivetted the fetters of his country. Under the fair pretences of relieving Italy from the heavy burden of military quarters, and of introducing a stricter discipline among the guards, he assembled them at Rome, in a permanent camp, which was fortified with skilful care, and placed on a commanding situation. “