A Clash of Civilisations is not inevitable, yet danger mounts the longer the West ignores its top forecaster. In 2023, the OECD sees China's economy as 27% bigger than the US: by mid-century 70%. India too will be larger, leaving America as No.3. Time to Get Real: listen to economists, especially development economists, and those in business who know China. Three giant shocks lurk right ahead for the West: economic, demographic and competence. 90% of the world's population will soon be non-Western: no more accepting exclusion from global decision making. After COVID, Afghanistan and domestic turmoil, many question Western competence to get things right, let alone avoid nuclear destruction. Economic size, not military might, is what counts among Great Powers. As leading military historian Paul Kennedy wrote, military strength is, "inextricably intertwined with economic power and technological progress". This need not threaten the West if understood and managed properly. Indeed, it would mitigate the real existential threats, from the environment to war. Otherwise nuclear conflict, Kissinger's "Armageddon-like clash", is ever more likely. A New New World with growing muscle and some different ideas is emerging. How can the West best respond? The book proposes a Biden-Xi Grand Bargain, as Nixon struck with Mao. Grasp what Yin and Yang offer, as opposites can support each other for lasting mutual benefit.