If a nation expects to be ignorant and free, in a state of civilization, it expects what never was and never will be. The functionaries of every government have propensities to command at will the liberty and property of their constituents. There is no safe deposit for these but with the people themselves; nor can they be safe with them without information. Where the press is free, and every man able to read, all is safe.

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

Letter (1816-01-06) to Charles Yancey
    (Source)

The original, non-orthographic version of this reads:

if a nation expects to be ignorant & free, in a state of civilisation, it expects what never was & never will be. the functionaries of every government have propensities to command at will the liberty & property of their constituents. there is no safe deposit for these but with the people themselves; nor can they be safe with them without information. where the press is free and every man able to read, all is safe.

There is a spurious variant on part of this quotation that reads:

If a nation expects to be ignorant and free, in a state of civilization, it expects what never was and never will be. If we are to guard against ignorance and remain free, it is the responsibility of every American to be informed.

While the first sentence (as above) is legitimate, the second is not. It appears to be a paraphrase of Jefferson used by Ronald Reagan in 1981.