Jethro Tull's first LP-length epic is a masterpiece in the annals of progressive rock, and one of the few works of its kind that still holds up decades later. Mixing hard rock and English folk music with classical influences, set to stream-of-consciousness lyrics so dense with imagery that one might spend weeks pondering their meaning -- assuming one feels the need to do so -- the group created a dazzling tour de force, at once playful, profound, and challenging, without overwhelming the listener. The original LP was the best-sounding, best-engineered record Tull had ever released, easily capturing the shifting dynamics between the soft all-acoustic passages and the electric rock crescendos surrounding them.