Of course, I like reading easy books. I read books for pleasure and one pleasure is being absorbed into a world, a set of characters and train of events so thoroughly that, while I'm reading it, I feel involved. I'm still reading Scandanavian crime fiction - wondering if Erlendur's life will become any more miserable and looking forward to the second volume in Stieg Larsson's Millennium trilogy.

But sometimes I'm not looking for escape or easy answers. I want a book that makes demands on me, that takes me somewhere I hadn't expected or presents me with problems I won't be able to resolve and put away as I reach the final page.

With some books, the subject, plot and characters linger powerfully. I'm still caught in the world of Hilary Mantel's Wolf Hall, which I finished only a few weeks ago. This is partly because it seems to present ethical dilemmas which resonate now: problems of wealth and poverty, the nature of influence in politics, the role of money and the market, the point at which the most well-intentioned individuals become complicit in violence and torture. But while these questions are raised, the novel also evokes a strong sense of the time and place in which it is set - it's a novel set around Henry VIII's court at the time of his obsession with Anne Boleyn.

Elsewhere the difficulty and the strangeness of part of the attraction. This is often at the level of language. I don't think I'll ever forget the delight I felt in opening a slim Penguin book in a small bookshop and finding the lines:

Welneȝe of al þe wele in þe west iles.

It's the opening of the anonymous mediaeval poem, Sir Gawain and the Green Knight, and something in the language enthralled me in a way that Chaucer never has. It was the difficulty and the sense of strangeness, I think.

At about the same time I found a copy of Teach Yourself Greek in the library and found myself sounding out the Greek word for sand - and that determined me to find a way of learning Classical Greek. I was never particularly good at it but in recent days I've picked up my Loeb parallel text of books 1-12 of the Odyssey and am wallowing in the pleasure of a language I don't fully understand and systems of customs and belief that are strange to me.

I've also returned to Finnegans Wake. It's famously difficult and I haven't got very far. I keep re-reading, relishing the language and catching the jokes. Yes! There are jokes in Finnegans Wake. Nobody warned me about that but I found them for myself. It happened as I was reading (for the third time) the passage which, I think, is about a visit to a Dublin museum with exhibits about the Duke of Wellington and the Battle of Waterlook. It begins like this, with the voice of the museum guide:

This the way to the museyroom. Mind your hats goan in! Now yiz are in the Willingdone Museyroom. This is a Prooshi-ous gunn. This is a ffrinch. Tip. This is the flag of the Prooshi— ous, the Cap and Soracer. This is the bullet that byng the flag of the Prooshious. This is the ffrinch that fire on the Bull that bang the flag of the Prooshious. Saloos the Crossgunn! Up with your pike and fork! Tip. (Bullsfoot! Fine!) This is the triplewon hat of Lipoleum. Tip. Lipoleumhat. This is the Willingdone on his same white harse, the Cokenhape. This is the big Sraughter Wil-lingdone, grand and magentic in his goldtin spurs and his ironed dux and his quarterbrass woodyshoes and his magnate’s gharters and his bangkok’s best and goliar’s goloshes and his pullupon-easyan wartrews. This is his big wide harse. Tip.

In Finnegans Wake it's necessary to hear someone else's voice and take the risk that all children take when learning to speak and read - the risk of not understanding everything all at once. Learning a language is like that too. We have to face moments of uncertainty and live with incomprehension. It's not a bad basis for life. I'd recommend more difficult books and more willingness to say "I'm not sure" or "I don't understand." After all, the alternative is clinging to the safety of the familiar and never daring to leave home.