I didn't bring a camera because I didn't think we were going to be allowed to take photos, let alone handle the books. But one chap in our group, a very nice German postdoc named Daniel Heisselmann, brought his Nikon dSLR and kindly sent me the pick of his shots when I requested them.
Not pictured: spiral staircase in the opposite corner for accessing the balcony running round the upper shelves. ♥ ♥ ♥
The gentleman to my write was our esteemed guide, the head librarian.
It's only a first edition of the Principia Mathematica.
He told us he didn't believe in using white gloves to handle the books because they make a person more clumsy and prone to tearing the pages.
All I could think was, "This is worth at least a quarter of a million pounds. Mustn't. Drop."
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To wind down the tour, he took us to the top floor of the library, gave us wine and showed us early photographic plates of the surface of the moon and solar eclipses. I don't think it really made us any less giddy, although after two solid hours of non-stop historical tuition, I think we were all quite tired. But it was certainly fantastic and a tremendous honour. I won't forget it.