The usual definition of 'sadism' is 'sexual pleasure derived from the infliction of pain and of cruelty to others', and De Sade's books provide many examples of such practices, but - for those not obsessed with it, as De Sade was - make boring and obnoxious reading.

The Marquis de Sade spent much of the second half of his life in a madhouse, where he wrote most of his books, apparently in an obsessive frenzy, and as an imaginary way to satisfy himself.

Those who want to get the general drift of his argument in his own words should read 'The Bedroom Philosophers' ('La Philosophie dans le boudoir'), since this is thin, not overly filled with endless descriptions of gruesome practices, and because it also is clear about ordinary hypocrisies, while De Sade, apart from his perversions, was an intelligent and educated man.

Also, it should be remarked that there is much more sadism in human beings than  most are willing to admit, especially if the term 'sexual' in the above definition is deleted: Very many people derive much pleasure from being in positions of power and by hurting, denigrating, demeaning or displeasing others using their position. It probably does not arouse most of them sexually, but they wouldn't do it if it did not please them. And this kind of pleasure seems to be one of the strongest motivators of those who desire to be boss: To let others feel they are inferior.

This 'human-all-too-human' desire to hurt, harm, demean and denigrate others is one of the normally unacknowledged forces of history, as is stupidity. It is probably the normal human reaction to personal unhappiness: Make others suffer at least as much as one does oneself.

Sadism as a sexual perversion seems fairly rare (especially in its more extreme forms), but as a perversion of character seems to be fairly common in bureaucrats, many of whom seem to do the boring work they do for the pleasures it brings in  exercising their power over others.