BIOGRAPHIES can be wearisome contrivances, often too long and too detailed for their own good. Biographers make the mistake of spending too much time worshipping at the altar of their subjects. Think of the magisterial, three-volume life of Robert Frost by Lawrence Thompson, for example, and how the biographer passed, over the many years of its making, from hero worship to intense dislike of the poet he shadowed for almost a quarter of a century. Yes, too long and intense an acquaintance can lead to sourness.

As the bicentenary of Charles Darwin's birth on February 12th approaches, it is good to welcome a biography which is relatively small, but in no way superficial or scanty. Ruth Padel has achieved this feat by writing her great-great-grandfather's life in a sequence of often quite short poems. Through her verses she seeks to capture the “voice” of Darwin, thus performing a difficult act of literary ventriloquism. Ms Padel, who often writes about animals, embeds many of Darwin's own words—from his books or his letters—in her poems, and the results tend to give the sense of being jointly authored. Sometimes she shapes entire gobbets of quotation into her own poetic passages. If this seems to be a bit of sly plagiarism, it doesn't feel like it. It feels more like a deft act of collaboration between the living and the dead, one melding easily with the other.

Why does this book work so well? How does it manage to say so much in so few words? Ms Padel seems to have caught the quintessence of the man's character, as if in a butterfly net. She enters into his cast of mind, bringing across his hypersensitivity, his sense of fragility, his lifelong nerviness, the way in which the canker of doubt about the credibility of religious doctrine ate away at him. The poems are a sequence of snapshots—often small, spasmodic and delicately imagistic—of particularly crucial incidents in his life; of moments of intellectual illumination.

One of the finest poems summarises his wonder at entering, for the first time, into pristine rainforest. It is a bit like a photograph album with audio commentary. The poems are wonderfully free of the drag and load of overbearing and perfectly useless detail with which so many second-rate biographies are stuffed to the gills. Most important of all, they seem to distil Darwin to his essence. He was a compulsively inquisitive child. He was also fearful. In part, he feared himself and his roving intellect. His inability to believe in the Christian god put him at odds with his beloved wife, Emma, and made him feel as if he lived set apart in some cold, far galaxy of the mind.

It is not easy to describe a whole life in relatively few words. You need to find some way of filling in the background. Ms Padel has overcome this problem by having paragraphs of notes run, in a single column, beside the texts of the poems so that they can be read side by side.

And why are poems a good way of illuminating a life such as Darwin's? The best lyric poems—think of Keats or Shelley, for example—are moments of epiphany, a sudden opening out onto magic casements. And Darwin, throughout, was in the grip of something very similar: a terrible, destabilising sense of wonder. He sensed intimations of the marvellous everywhere he looked. All the sadder then—and this is something that Ms Padel does not explain—that, later in life, the man who carried with him on the Beagle a copy of Milton's “Paradise Lost” found that he could no longer enjoy poetry.