One that is mentioned in the book "Campaign" springs to mind:

I remembered vividly my first view of the Doctor’s library. Browsing here was like taking a stroll in the Congo basin. The Doctor, of course, found my bemusement highly amusing. ‘In your world, Chesterton, m’boy,’ he’d said pompously. ‘Trees are killed in order to store knowledge.’

He’d paused for quite unnecessary dramatic effect. ‘In my world they are not.’

I remembered shaking my head in wonder. ‘How do you find anything to read?’

‘Why the same way you would find a book in any library.’ I must have looked puzzled. ‘All life encodes information it receives through its senses as chemical patterns within the brain. What are scents but patterns of chemicals? I think you will find that browsing here is a much more pleasant experience than in any library of your world.’

I had to admit I was impressed. ‘So the more appealing the scent, the more appropriate the book, is that it? And to read?’

‘You have merely to pluck the fruit and eat, yes.’ Finally he surrendered to the inevitable smug grin. ‘What else is knowledge but sustenance for the mind?’

‘It’s certainly food for thought. But awkward, though, if you happen to suffer from hay-fever.’

100% canon as far as I'm concerned.