Grandad, we love you

Patricia Fara salutes polymath Erasmus Darwin.

Through its frequent reproduction on dust jackets, Joseph Wright's painting of An Experiment with a Bird in the Air Pump has become wearingly familiar to everyone with an interest in science. Far less well known, however, is the probable model for the man at the left front holding a watch - Erasmus Darwin. Like many 18th-century men, Darwin was eminent among his contemporaries, but has often been relegated to a supporting role in the biographies of people now judged more important. His theory of evolution, for instance, has been appraised mainly for its effects on his far more famous grandson, Charles, while literary critics have pored over his heavily annotated scientific poetry in order to analyse its relationship with Frankenstein : both the Shelleys used Erasmus Darwin's name to lend this novel scientific credibility.

Although afflicted by a severe stammer, Darwin was apparently extremely popular among his colleagues and patients, and particularly attractive to women. A man of immense exuberance and energy, he engaged enthusiastically in many different projects. As well as being a dedicated family doctor, he designed carriages, speaking machines, windmills and artificial birds, and at the same time published numerous scholarly books and papers on subjects ranging from squinting, dropsy and evolution to canals, female education and gardening. He also wrote many poems, most famously three book-length epics that lyrically covered topics as diverse as Linnaean plant classification, steel manufacture and the origins of society, and whose allegorical didacticism was reinforced by learned essays on subjects like chemistry, electricity and language theory. Thanks to this huge spread of his interests, Darwin has now been rescued from his former dependent status as Charles's grandfather. Instead of being dismissed as the whimsical creator of "a bizarre tale of gaudily dressed characters engrossed in various forms of polygamy", Erasmus Darwin is now recognised as an influential author and an important man of science who made vital contributions to the early stages of English industrialisation.

During the past 30 years, Desmond King-Hele has written several books about Darwin, as well as publishing transcripts of his papers and letters and being instrumental in a project to restore Darwin's house in Lichfield and open it as a museum. Himself a distinguished space scientist, King-Hele has endeavoured to promote an image of Darwin as an ingenious inventor and scientific innovator whose ideas often prefigured those of modern science. He has also explored Darwin's influence on the English Romantic poets, comparing textual extracts to show (with varying degrees of plausibility) that Coleridge, Blake, Wordsworth, Keats and Shelley all borrowed ideas and imagery directly from Darwin's poetry and from Zoonomia , his weighty two-volume treatise on animal classification and diseases.

Benefiting from King-Hele's pioneering studies, other historians have provided rather different analyses. Most significantly, Maureen McNeil has presented a more politically nuanced study, focusing on Darwin's involvement with the Lunar Society and his associations with the wealthy landed entrepreneurs who were successfully developing new industrial processes and agricultural techniques. As she and Janet Browne have separately pointed out, Darwin's poetry contains some eloquent silences: in the rustic paradise of his Botanic Garden , there are neither impoverished labourers nor scenes of sexual violence to disturb the sensibilities of his middle-class readers.

The orientation of King-Hele's latest biography, Erasmus Darwin: A Life of Unequalled Achievement , is well captured by its subtitle. While the incomplete bibliography unfortunately belies the wealth of published and manuscript sources King-Hele has consulted, his most valuable new perspectives are derived from his own edition of Darwin's letters, and from a previously unutilised cache of family papers recently donated to Cambridge University Library. As a consequence, King-Hele has been able to furnish a far fuller account of Darwin's personal life. In addition to details of Darwin's two marriages, he relates the "goings-on" with Darwin's mistress Mary Parker (assumed to be "a nifty number rather than a po-faced puritan") under the watchful eyes of his sister and the jealous Anna Seward, quotes letter extracts to convey the closeness of his ties with members of the Lunar Society, and reveals concealed aspects of Darwin's character by letting his subject speak for himself. We now have a far more intimate portrait of yet another version of Darwin, the committed physician and sensitive family man who revelled in his sexual liaisons, yet grieved deeply over the deaths of his first wife and two of his three sons, one a promising medical student at Edinburgh, the other a middle-aged man plagued by unsettled debts.

This is a traditionally structured biography, which starts with the family's 16th-century origins, progresses chronologically through Darwin's childhood and adult life to reach his "metamorphosis" into "a sexy poet" at the age of 57, and then continues on beyond the "Downhill" chapter to review his posthumous legacy and evaluations. Along the way, King-Hele adduces ample testimony from Darwin's contemporaries to corroborate his own open admiration for Darwin's achievements. Coleridge reported that "Dr Darwin possesses, perhaps, a greater range of knowledge than any other man in Europe", while Horace Walpole enthused that he could "read this over and over again forever ... all, all is the most lovely poetry". Unlike them, King-Hele can judge Darwin retrospectively from the standpoint of modern science, and although he does censure Darwin for his old-fashioned errors, we learn that this poet who coined the word "flagellate" also pioneered the motor car, presciently carried out research necessary to develop the hovercraft, and preempted by almost 200 years Steven Weinberg's big-bang description of the early universe.

King-Hele delights in understated humour and selects his quotations with care:

"Mr S died of sore throat, which retreated and fell on the brain." He describes Josiah Wedgwood's habit of angrily smashing substandard pottery with his wooden leg, and drily records that Darwin "had made the mistake of riding naked into town at Nottingham, but he did not repeat the error". While replete with anecdotes, love poems and letters, this book is also intended to be an intellectual biography for those who know little about the history of science, since King-Hele interweaves his narrative of Darwin's life with thumbnail sketches of medical, scientific and technological knowledge in the 18th century.

King-Hele has created a moving and amply researched narrative of a man who for him has acquired a heroic stature. It will undoubtedly prove an invaluable resource for a future biographer choosing to adopt a more thematic approach.

Patricia Fara is a fellow, Clare College, Cambridge.