The pictured letter, dated 31 March 1791, is from Erasmus Darwin to Edward Jerningham. The publication of Darwin’s two-part paean to science, The Botanic Garden, was imminent; he wrote to Jerningham (who sometimes sent him poems as part of their correspondence) to advise him that a small portion of that long poem might look familiar.                     

In my next poem, which is now printing, and I suppose will be out in 6 or 8 weeks, I shall borrow something from your Il Latte, but not without acknowledgements. I hope you will continue to write. I think I have exhausted my stock.                     

True to his word, Darwin includes in the poem a footnote giving credit to Jerningham’s ‘elegant little poem […] exhorting ladies to nurse their own children’.                      

Having explained how breastfeeding functions (by way of ‘an incipient vacuum’), Darwin looks to Jerningham to argue for its importance. Yet lines from ‘Il Latte’ are not copied directly. Darwin takes an eight-line portion and fits it into six, aided by deploying couplets rather than the original’s alternate rhyme, whose formal clinches necessarily take longer to reach. ‘Ah! what avails the coral crown’d with gold?’ asks Jerningham; Darwin prefers ‘the cradle’s damasked roof’, but goes on to construct essentially the same point, which is that an infant cares infinitely less for chilly finery than for maternal nurture and nourishment. Darwin is modest, however in saying that his passage is ‘from’ Jerningham’s effort. He is careful to avoid reproducing specific images of the child’s surroundings, and introduces a fresh observation ...