The career of Erasmus Darwin (1731-1802) affords an extraordinary glimpse into the intellectual ferment of late-eighteenth- and early-nineteenth-century Britain. As a popular poet, practicing physician, inventor of speaking machines and mechanical birds, essayer of natural history from geology to meteorology, and proponent of an evolutionary theory that inspired his famous grandson Charles, he left a lasting impression on almost every branch of knowledge. His magnum opus, and the synthesis of his myriad interests, is The Botanic Garden (1792) -- an epic poem that aims to "enlist the...