I was able to attend only the last of Penelope Curtis’s Mellon Lectures at the National Gallery tonight.   The series as a whole was called Sculpture on the Threshold and has been about the way that sculpture is viewed and constructed in different settings and in space.   The last was entitled The Ensemble and, like – I assume – the rest, ranged widely historically and provocatively, including The Temple of the Four Winds at Castle Howard, Stourhead, as well as contemporary work, Roger Hiorns and Rosemarie Trockel, not always understood as formally related, ending up, as she began, with Rilke.   I wish I had been able to go to them all.