John Greenleaf Whittier was an abolitionist who was one of the founding members of the American Anti-Slavery Society. Amongst many things he did for the cause, he published a pamphlet titled Justice and Expediency in which he called for an immediate end to slavery and was an outspoken lobbyist for the abolitionist cause.
His opinions on slavery were most probably influenced by Lloyd Garrison who had encouraged Whittier to get a formal education. Garrison was abolitionist and as he and Wittier became close, convinced him to become one as well.
