His first and second books, Land of Unlikeness (Harcourt, Brace and Company,1944) and Lord Weary’s Castle (Harcourt, Brace and Company,1946) , for which he received a Pulitzer Prize in 1947 at the age of thirty, were influenced by his conversion from Episcopalianism to Catholicism and explored the dark side of America’s Puritan legacy.
Lowell was politically involved: he became a conscientious objector during the Second World War (was imprisoned as a result) , and actively protested against the war in Vietnam. He suffered from severe episodes of manic depression, for which he was repeatedly hospitalized.
Partly in response to his frequent breakdowns, and partly due to the influence of younger poets as W. D. Snodgrass and Allen Ginsberg, Lowell in the mid-1950s began to write more directly from personal experience, and loosened his adherence to traditional meter and form.
The result was a watershed collection, Life Studies (Faber and Faber,1959) , which forever changed the landscape of modern poetry, much as Eliot‘s The Waste Land had three decades before.