It’s hard to imagine The Queen as a little girl in smocked, frilly dresses, or as a quiet teenager flirting with a boisterous young Philip, or as an 18-year-old truck mechanic in WW1. It’s hard to imagine her as anything other than an elderly lady with white curls, pastel hats and her signature Launer handbags. In celebration of The Queen’s 90th birthday I choose this image, shot by photographer Lisa Sheridan, of a young, modern Princess Elizabeth sitting at her desk at Buckingham Palace in 1946. “I declare before you all that my whole life, whether it be long or short, shall be devoted to your service,” she said in Cape Town a year later. Here’s to a long, devoted, formidable life. Happy Birthday, Ma’am.

I’ve been thinking about impermanence in art lately, ephemeral creations like sandcastles, mandala and flower carpets that exist only for an hour, for a day or for a few weeks. It’s sort of heartbreaking to think of a person pouring so much heart, sweat and gut into an art installation that lasts a month. But the concept, the process, the triumph of completion and the hope and promise of what comes next can all be so richly fulfilling. Christo, the Bulgarian artist who creates huge scale environmental works of art has said that wrapping an object, much like losing a loved one, (his wife and collaborator Jeanne-Claude died suddenly in 2009) can vividly reveal the transience of our own existence: “Our projects attract people who come there to see something about which they can say, ‘I saw it, and if you don’t see it, it will never happen again. Tomorrow it will be gone forever, like our lives.’ ”