Niccolò Machiavelli
Discourses on the First Decade of Titus Livius (Chap. 3.2)
That on occasion it is wise to feign Folly.

Never did any man by the most splendid achievements gain for himself so great a name for wisdom and prudence as is justly due to Junius Brutus for feigning to be a fool. And although Titus Livius mentions one cause only as having led him to assume this part, namely, that he might live more securely and look after his patrimony; yet on considering his behavior we may believe that in counterfeiting folly it was also his object to escape notice, and so find better convenience to overthrow the kings, and to free his country whenever an occasion offered. That this was in his mind is seen first of all from the interpretation he gave to the oracle of Apollo, when, to render the gods favourable to his designs, he pretended to stumble, and secretly kissed his mother earth; and, again, from this, that on the death of Lucretia, though her father, her husband, and others of her kinsmen were present, he was the first to draw the dagger from her wound, and bind the bystanders by oath never more to suffer king to reign in Rome.

From his example all who are discontented with their prince are taught, first of all, to measure, and to weigh their strength, and if they find themselves strong enough to disclose their hostility and proclaim open war, then to take that course as at once the nobler and less dangerous; but, if too weak to make open war, then sedulously to court the favour of the prince, using to that end all such methods as they may judge needful, adapting themselves to his pleasures, and showing delight in whatever they see him delight in. Such an intimacy, in the first place, enables you to live securely, and permits you, without incurring any risk, to share the happy fortunes of the prince, while it affords you every facility for carrying out your plans. Some, no doubt, will tell you that you should not stand so near the prince as to be involved in his downfall; nor yet at such a distance that when he falls you shall be too far off to use the occasion for rising on his ruin. But although this mean course, could we only follow it, were certainly the best, yet, since I believe it to be impracticable, we must resort to the methods above indicated, and either keep altogether aloof, or else cleave closely to the prince. Whosoever does otherwise, if he be of great station, lives in constant peril; nor will it avail him to say, "I concern myself with nothing; I covet neither honours nor preferment; my sole wish is to live a quiet and peaceful life." For such excuses, though they be listened to, are not accepted; nor can any man of great position, however much and sincerely he desire it, elect to live this life of tranquillity since his professions will not be believed; so that although he might be contented to be let alone, others will not suffer him to be so. Wherefore, like Brutus, men must feign folly; and to play the part effectively, and so as to please their prince, must say, do, see, and praise things contrary to their inclinations.

But now, having spoken of the prudence shown by Brutus when he sought to recover the freedom of Rome, let us next speak of the severity which he used to maintain it.