Over the last half century, a quiet revolution has taken place. In a series of breathtaking discoveries, biochemist Thomas Cech and a diverse cast of brilliant scientists have revealed RNA at the centre of biology’s greatest mysteries, from how life began to what makes us human to why we age. At last, The Catalyst pulls back the curtain to show how RNA—long sidelined as the passive servant of DNA—defines life from its very origins to our future in the twenty-first century. Recounting his own paradigm-shifting discovery that RNA can catalyse biochemical reactions, as well as his work on the “fountain of youth” telomerase, Cech unfolds how RNA holds the key to the intricate machinery of our cells, the critical processes of ageing and disease and the spectacular powers of breakthrough therapies from CRISPR to mRNA vaccines. From one of our foremost scientists, The Catalyst is a must-read guide to the present and future of biology and medicine.