I REALLY like the following:

To announce that there must be no criticism of the president, or that we are to stand by the president right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public.
Theodore Roosevelt

We must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military-industrial complex. The potential for the disastrous rise of misplaced power exists and will persist.
Dwight D. Eisenhower

People who don't vote have no line of credit with people who are elected and thus pose no threat to those who act against our interests.
Marian Wright Edelman