As a self-confessed Darwin groupie, I own an extensive collection of books by and about my hero and his friends and colleagues. Many of these books are still in print, but I have inevitably acquired a number of out-of-print, second-hand books.

One of the delights of second-hand books is coming across the inscriptions and marginalia of their previous owners. Often, the reason for a mark or underlining escapes me—why on earth did they think that particular passage was worth highlighting? Sometimes, the notes are illegible. Very occasionally, they can be (melo)dramatic.

Last weekend, leafing through my abridged copy of Sir Francis Darwin's Life and Letters of Charles Darwin, I encountered numerous brief notes in the margins, all in the same hand. Here's a selection:

• reading + lectures
• !!!!
• industry + concentrated attention
• Wordsworth
• collection of facts
• Put it down!!
• novel reading
• Respect for TIME!
• a Naturalist
• age of the world
• Boy Chimney Sweep
• Fame! & Instinct!
• Huxley approves
• [my favourite] Poor Sedgwick

I will never know who the previous owner of my book was, but it seems pretty obvious to me that they were a fellow Darwin groupie: the book has clearly been read from cover to cover, with considerable enthusiasm, and the passages marked are often the sorts of passages I would mark.

Only I wouldn't. I could never bring myself to write in a book, you see. It's just not the done thing. Instead, when I'm reading a book, I make notes on index cards, which double as convenient bookmarks. Once I've finished the book, I tuck the card away inside the back cover for future reference. Yes, loose cards can be lost, but writing in books, well… you just don't! It's not how I was brought up. Books are precious objects to be cosseted, not abused.

And then I turn to page 96 of Sir Francis's memoir, and find myself frankly aghast at the following passage about my hero:

For books he had no respect, but merely considered them as tools to be worked with. Thus he did not bind them, and even when a paper book fell to pieces from use, as happened to Müller's Befruchtung, he preserved it from complete dissolution by putting a metal clip over its back. In the same way he would cut a heavy book in half, to make it more convenient to hold. He used to boast that he had made Lyell publish the second edition of one of his books in two volumes, instead of in one, by telling him how he had been obliged to cut it in half.

Cutting a heavy book in half… Darwin groupie though I will forever remain, here I draw the line. Mr Darwin, you were a incorrigible vandal, sir!

The scene of many a book desecration: Darwin's study at Down House