It lifts your soul to see this joyful painting in Edinburgh’s National (as the Scottish National Gallery is now known) as this 18th century minister of the city’s Canongate Kirk seems to levitate and glide among less mobile canvases. Ice skating in art had never been so graceful before. In Dutch paintings, it’s more about thickly coated kids mucking about at ice fairs. But this was the Scottish Enlightenment, when reason was applied to everything from history to medicine by Edinburgh’s leading intellects. Walker seems to apply that same Enlightened spirit in his sport: he charms the wilds of nature and makes the harsh winter his friend.