My friendship with Freeman Dyson goes back over a half century. My first contact with him goes back to the late 1950s, when I was at the Institute for Advanced Study, and then evolved when I was a consultant at General Atomics in La Jolla, California. Freeman was then trying to design a space ship - the Orion - which would be propelled by atomic bombs. When I left the Institute, Freeman and I continued our correspondence and I saved his letters. They are written in an almost calligraphically elegant handwriting. It is hard to see how you could make a mistake in a mathematical computation if you wrote that clearly. The letters show his human side and his enormous range of knowledge.

There are then two essays involving the physicist Fritz Houtermans who was an extraordinarily colorful character. There is a brief essay on Einstein’s collaboration with a fraud. There is even an essay on the Titius-Bode law and the new exo-planets. Because of my enduring interest in nuclear weapons, the reader will find essays devoted to that. There is also a bit of fiction at the end.