Born in Ireland in the mid-nineteenth century, Agnes Mary Clerke achieved fame as the author of A History of Astronomy during the Nineteenth Century. Through her quarter-century career, she became the leading commentator on astronomy and astrophysics in the English- speaking world. The biography of Agnes Clerke describes the life and work of this extraordinary woman. It also chronicles the development of astronomy in the last decades of pre-Einstein science, and introduces many of the great figures in astronomy of that age including Huggins, Lockyer, Holden, and Pickering; their achievements and their rivalries. The story follows her friendship with William and Margaret Huggins, and her prolific correspondence with eminent astronomers of the time. This biography will fascinate scientists, and anyone who admires intellectual achievement brought about through love of learning and sheer hard work.