Scarcity.

I am more and more convinced that Man is a dangerous creature, and that power whether vested in many or a few is ever-grasping, and like the grave cries give, give. The great fish swallow up the small, and he who is most strenuous for the Rights of the people, when vested with power, is as eager after the prerogatives of Government. You tell me of degrees of perfection to which Humane Nature is capable of arriving, and I believe it, but at the same time lament that our admiration should arise from the scarcity of the instances.

Abigail Adams, from a letter to John Adams, 27 October 1775