At that point, we were allowed to walk past the security (who studiously examined all our bags), and into the second floor library -- where, we could clearly see the signs posted over the bookshelves:

DO NOT TOUCH THE BOOKS! A MOTION SENSOR WILL BE ACTIVATED AND THE LIBRARY WILL BE LOCKED DOWN!

What a beatiful way to introduce the library!

In the end, all we were allowed to do, was stand about 5 m away from the first row of books, and peer down the corridors of books beyond that.

At the start of one of the corridors, our guide explained that, originally, the books had all been chained to the desks. This was to protect them from being stolen by scholars. She said that Oxford's Bodleian had been founded as a way to combat this, and provide learning for all.

Next to her, the sign stated clearly:

DO NOT TOUCH THE BOOKS! A MOTION SENSOR WILL BE ACTIVATED AND THE LIBRARY WILL BE LOCKED DOWN!

Some learning for all!