When a man assumes a public trust, he should consider himself as public property, and justly liable to the inspection and vigilance of public opinion; and the more sensibly he is made to feel his dependence, the less danger will there be of his abuse of power.

Thomas Jefferson (1743-1826) American political philosopher, polymath, statesman, US President (1801-09)

Conversation with Baron Humboldt (1807)
    (Source)

In Seymour, A Winter in Washingtonm ch. 9 (1824), further identified in Raynor, Life of Jefferson (1832). As it is all anecdotal, the accuracy may be easily questioned, but its proximity to the events lends it a certain validity.