Julie de Thellusson-Ployard, 1760

After the film yesterday, I walked through Soho to the Royal Academy (passing Foyle's, where I finally gave in and treated myself to a very expensive book that I've wanted for ages). I ignored the throng milling around for Ai Weiwei, though I might go back - his tree sculpture in the courtyard looks wonderful. But I was more in the mood for the extraordinary pastels of Jean-Etienne Liotard. We don't know him better because it has only recently become possible to transport pastels without damaging them. This is the most engaging exhibition I've seen for ages. Not just the medium - what a master he was, you wouldn't think you could achieve such extraordinary detail with pastel - but the wonderful intimacy and liveliness of his portraits. Look at this bridal portrait of Julie de Thellusson-Ployard, aged about 20 (that's her husband's portrait on her wrist) ... Doesn't she look fun, and not likely to say no to a second slice of cake!

And this is Princess Louisa-Anne, aged five, the sickly delicate child of the late Frederick, Prince of Wales and Princess Augusta. He captures her alert, lively curiosity at the same time as her wan peakiness ... see how thin she is, that dress is so big for her that it's slipping down her chest below her nipple. I kept thinking that if you stripped off the expensive gown, she'd look like an under-nourished  slum child.

While I was there, I stepped in to the library to see Edmund de Waal's display White. There is nothing whiter than a white page, nothing quieter than a library, he says ... err, no, not any more, because the effect was rather spoiled by the constant clickety-clack of computer keyboards. It is beautifully hung with mirrors - and I was delighted to see the famous Hare with Amber Eyes - but this is a tiny display, you'll be in and out in ten minutes, and unless you're a member  I think you'd feel pretty miffed at paying a fiver. Don't think it would have killed the RA to make this one admission free.