What is the smallest thing we can see? The fundamental limit on the size of an object that can be visualized with a light microscope is typically about half a micrometre. In this book of articles based on recent Evening Discourses at the Royal Institution, Akira Tonomura explains how electron waves can be harnessed to unveil the hitherto invisible microcosmos. Elsewhere in this volume Lewis Wolpert writes on the unnatural nature of Science, Harold Kroto retells the events leading to the discovery of buckminsterfullerene, and Tony Benn discusses science and political power. These and other essays are authoritative and accessible summaries of current thinking in many areas of science and technology.