When Jared Kushner met Henry Kissinger in 2016 he prepared a memo for Donald Trump’s presidential campaign, distilling the diplomat philosopher’s words into bullet points. Avoid giving yes or no answers to complex diplomatic suggestions was one of the nuggets. And always try to work out whether the person on the phone holds real power or is just using you to build influence at home. It was the start of Mr Kushner’s training in diplomacy that this week saw him deliver a breakthrough in the Middle East and a deal that could end the conflict in Gaza. His use of...