The Quakers, who, from the early colonial days, had been strongest in their expressions against slavery, formed the first Anti-Slavery Society in the United States at Philadelphia in 1775. The Revolution interrupted their work, but at its conclusion they resumed their efforts patiently and incessantly, year after year, in their attempts to arouse the public mind to the enormity and dangerousness of the slave evil. Although other States organized anti-slavery societies immediately after the Revolution, the Pennsylvania Society took the leading part, and was comparatively alone for many years in the work. In the First Congress this Society presented a Memorial, asking Congress to exercise its utmost powers for the abolition of slavery. The subject was the occasion of a heated debate, and Congress decided that under the Constitution it could not, prior to 1808, abolish the slave trade; but that it had authority to prevent citizens of the United States from carrying on the African slave trade with other nations (a law to this effect was subsequently passed); and that it had no authority to interfere with the emancipation of slaves or their treatment in any of the States. The Pennsylvania Society watched Congress closely and worked along patiently year after year, meeting with failure after failure. This early Abolition movement had among its supporters the foremost men of the day --Washington, Jefferson, Franklin, Hamilton, Jay and Henry are some of the illustrious names connected with the movement, just as in England the names of Burke, Fox and Pitt are recorded against the iniquity. When the purchase of the Louisiana Territory came before Congress, the Pennsylvania Society petitioned that measures should be taken to prevent slavery in the new territory, but the Federalists were more engrossed with a discussion of Constitutional questions, and the opportune moment went by without any action on the matter.