Measuring Tomorrow is about ending our passion for growth and engaging in the well-being and sustainability transition. Growth of Gross Domestic Product, or GDP, captures only a tiny fraction of what goes on in complex human societies: it tracks some but not all of economic well-being (saying nothing about fundamental issues such as income inequality); it does not account for most dimensions of well-being (think about the importance of health, education or happiness for your own quality of life); and it does not account at all for sustainability, which basically means well-being not just today but also tomorrow (imagine your quality of life on a planet where the temperature would be four degrees higher or where there would be scant drinkable water or breathable air). This book’s essential argument is that well-being (human flourishing), resilience (resisting to shocks) and sustainability (caring about the future) should become the collective horizons of social cooperation instead of growth. And it offers powerful tools, dozens of examples from all corners of our world, and practical ways to achieve this goal.To put it differently, while policymakers govern with numbers and data, they are as well governed by them, so they better be relevant and accurate. It turns out, and I think that’s a strong argument of the book, that GDP’s relevance is fast declining in the beginning of the twenty-first century for three major reasons. First, economic growth, so buoyant during the three decades following the Second World War, has gradually faded away in advanced and even developing economies and is therefore becoming an ever-more-elusive goal for policy. Second, both objective and subjective well-being—those things that make life worth living—are visibly more and more disconnected from economic growth. Finally, GDP and growth tell us nothing about the compatibility of our current well-being with the long-term viability of ecosystems, even though it is clearly the major challenge we and our children must face.Since “growth” cannot help us understand, let alone solve, the two major crises of our time, the inequality crisis and ecological crises, we must rely on other compasses to find our way in this new century. In my view, the whole of economic activity, which is a subset of social cooperation, should be reoriented toward the well- being of citizens and the resilience and sustainability of societies. For that to happen, we need to put these three collective horizons at the center of our empirical world.