Erasmus Darwin's 1791 poem The Botanic Garden established him for a period as the leading English poet of his day,[30] and was a major influence on the Romantic poetry of William Blake, William Wordsworth, Samuel Taylor Coleridge, Percy Bysshe Shelley, and John Keats.[30] Thomas Day – an ardent follower of the French philosopher Jean-Jacques Rousseau – wrote an early series of radical poems including the anti-slavery work The Dying Negro (with John Bicknell) in 1773, and a passionate defence of the American Revolution The Devoted Legions in 1776.[31] He is however best known for his books for children, particularly his 1789 work Sandford and Merton, which remained the most widely read and influential children's book for a century after its publication,[32] and whose proto-socialist outlook was "to play a crucial role in moulding the ethos of nineteenth-century England".[31] Joseph Priestley wrote voluminously on an exceptionally wide range of subjects including theology, history, education and rhetoric.