« We rarely hear, it has been said, of the combinations of masters, though frequently of those of workmen. But whoever imagines, upon this count, that masters rarely combine, is as ignorant of the world as of the subject. Masters are always and every where in a sort of tacit, but constant and uniform combination, not to raise the wages of labour above their actual rate. To violate this combination is every where a most unpopular action, and a sort of reproach to a master among his neighbors and equals. We seldom, indeed, hear of this combination, because is the usual, and one may say, the natural state of things which nobody ever hear of. Master too sometimes enter into particular combinations to sink the wages of labour even below this rate. These are always conducted with the utmost silence and secrecy till the moment of execution, and when the workmen yield, as they sometimes do, without resistance, though severely felt by them, they are never heard of by other people ».
Adam Smith, The Wealth of the Nations. The Modern Library, New York, 1937 ; pages 66-67.