Montesquieu, after having recommended this rule of proportion, adds, “Quand il n’y a point de difference dans la peine, il faut en mettre, dans l’esperance de la grâce; en Angleterre, on n’assassine point (il auroit du dire peu), parce que les voleurs peuvent esperer d’être transportés dans les colonies, non pas les assassines.—Esprit des Lois, lib. 6, ch. xvi.

This expectation of favour, no doubt, contributes to the effect of which he speaks, but why should this manifest imperfection in the laws remain, that it may be corrected by an arbitrary act of the sovereign? If an uncertain advantage produces this measure of good, a certain advantage would operate more surely.