Charlie Pierce often posts James Madison quotes:
The free men of America did not wait till usurped power had strengthened itself by exercise, and entagled the question in precedents. They saw all the consequences in the principle, and they avoided the consequences by denying the principle. We revere this lesson too much soon to forget it. Who does not see that the same authority which can establish Christianity, in exclusion of all other Religions, may establish with the same ease any particular sect of Christians, in exclusion of all other Sects? that the same authority which can force a citizen to contribute three pence only of his property for the support of any one establishment, may force him to conform to any other establishment in all cases whatsoever?
-- James Madison, Memorial And Remonstrance Against Religious Assessments, 1785.