In order to subdue his subjects, the Prince labours to blind them. Conscious of the unlawfulness of his own designs, and sensible of what he has to fear from clear-sighted men, he endeavours to deprive the people of every means of acquiring knowledge.
How many crafty devices have not Princes employed to oppose the progress of learning? Some banish science out of their dominions; others prohibit their subjects from traveling into foreign countries; others again divert the people from reflecting, by continually entertaining them with feasts and shews, or keeping up among the the spirit of gaming; and all stand up against men of spirit, who dedicate either their voices or their pen to defend the cause of liberty.

[Persuadés d’ailleurs combien il est commode de régner sur un peuple abruti, ils [les princes] s’efforcent de le rendre tel. Que d’obstacles n’opposent-ils pas au progrès des lumières? Les uns bannissent les lettres de leurs Etats; les autres défendent à leurs sujets de voyager; d’autres empêchent le peuple de réfléchir, en l’amusant continuellement par des parades, des spectacles, des fêtes, ou en le livrant aux fureurs du jeu. Tous s’élèvent contre les sages qui consacrent leur voix et leur plume à défendre la cause de la liberté.]

Jean-Paul Marat (1743-1793) French physician, political theorist, scientist, journalist

The Chains of Slavery (Les Chaînes de L’Esclavage, ch. 40 “Of Ignorance” (1774) [Beckett ed. (1774)]
    (Source)

Source (French)). Other translations:

As sovereigns are persuaded of the convenience of ruling an ignorant people, they try to make it so. What won’t they do to prevent the progress of knowledge? Some banish anyone scholarly from their nation; others ban their subjects from traveling; others don't give the people the time to think, constantly amusing them with parades, shows, festivals, or by delivering them over to the passion for games. All of them denounce the wise who give their voice and pen to defend the cause of freedom.

Convinced, moreover, how convenient it is to reign over a stupefied people, they [princes] strive to make them so. How many obstacles do they not place in the way of progress of enlightenment? Some banish letters from their states; others forbid their subjects from traveling; others prevent the people from thinking, by continually amusing them with parades, spectacles, festivals, or by delivering them to the furies of gambling. All rise up against the wise men who devote their voice and their pen to defending the cause of liberty.
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