This book addresses the current challenges of sustainable development, including its social, economic and environmental components. The author argues that we need to develop a new concept of time based on inter-generational solidarity, which focuses both on the long- and the short term. The evolution of man's notions of time are analyzed from prehistory to modern times, showing how these concepts shape our worldviews, our ecological paradigms and our equilibrium with our planet. Practical approaches to dealing with the major medium- and long term sustainability challenges of the 21st century are presented and discussed. This is a thought provoking and timely book that addresses the main global socioeconomic and environmental challenges facing the current and future generations, using science-based analysis and perspectives. It presents an historical narrative of the advent of progress, economic growth and technology, and discusses the structural changes needed to co-create sustainable pathways. It provides hope for our future on Earth, mankind's common home. António Guterres, Secretary-General of the United Nations.