It may be alleged, that the same man may change his principles; and that he, who was once deservedly commended, may be afterwards satirized with equal justice; or that the poet was dazzled with the appearance of virtue, and found the man whom he had celebrated, when he had an opportunity of examining him more narrowly, unworthy of the panegyrick which he had too hastily bestowed; and that as a false satire ought to be recanted, for the sake of him whose reputation may be injured, false praise ought likewise to be obviated, lest the distinction between vice and virtue should be lost, lest a bad man should be trusted upon the credit of his encomiast, or lest others should endeavour to obtain the like praises by the same means.

But though these excuses may be often plausible, and sometimes just, they are very seldom satisfactory to mankind; and the writer, who is not constant to his subject, quickly sinks into contempt, his satire loses its force, and his panegyrick its value; and he is only considered at one time as a flatterer, and as a calumniator at another.

The Works of Samuel Johnson, LL.D. in Nine Volumes — Part 92

To avoid these imputations, it is only necessary to follow the rules of virtue, and to preserve an unvaried regard to truth. For though it is undoubtedly possible that a man, however cautious, may be sometimes deceived by an artful appearance of virtue, or by false evidences of guilt, such errours will not be frequent; and it will be allowed, that the name of an author would never have been made contemptible, had no man ever said what he did not think, or misled others but when he was himself deceived. The Author to be let was first published in a single pamphlet, and afterwards inserted in a collection of pieces relating to the Dunciad, which were addressed by Mr. Savage to the earl of Middlesex, in a dedication[76] which he was prevailed upon to sign, though he did not write it, and in which there are some positions, that the true author would, perhaps, not have published under his own name, and on which Mr. Savage afterwards reflected with no great satisfaction; the enumeration of the bad effects of the uncontrouled freedom of the press, and the assertion that the "liberties taken by the writers of journals with their superiours were exorbitant and unjustifiable," very ill became men, who have themselves not always shown the exactest regard to the laws of subordination in their writings, and who have often satirized those that at least thought themselves their superiours, as they were eminent for their hereditary rank, and employed in the highest offices of the kingdom. But this is only an instance of that partiality which almost every man indulges with regard to himself: the liberty of the press is a blessing when we are inclined to write against others, and a calamity when we find ourselves overborne by the multitude of our assailants; as the power of the crown is always thought too great by those who suffer by its influence, and too little by those in whose favour it is exerted; and a standing army is generally accounted necessary by those who command, and dangerous and oppressive by those who support it.

The Works of Samuel Johnson, LL.D. in Nine Volumes — Part 92