I contemplated a statement introducing this book to the reader, but on further thought I realized that the book introduces itself and speaks for itself all the way through. I will only say that Mary Craig Kimbrough was my wife for almost half a century. She guarded me, managed me, and worried about me during that period—for the task was an unending one. I was often engaged in politically and socially dangerous tasks, and Craig was the one who realized the dangers and undertook the task of saving me. This went on all through our marriage, and in the end her heart weakened, and for almost ten years I dropped all my other tasks and devoted myself to keeping her alive. She died in April, 1961. I wrote the text of _Mental Radio_, 1929, under her direction; she revised every word and had it exactly the way she wanted it. She was the most conscientious and morally exacting person I have ever known. Loyalty to the truth was her religion; and every sentence in this book was studied so that it would be exactly true and so clear that nobody could misunderstand it. She knew just how we did our experiments; she had told me exactly what to do, and I had done it; if I set it down wrong in the manuscript, she made it right. She has told of her early psychic experiences, and they were enough to fill her with determination to make sure they were real, and if possible to find out what they meant. It was she who laid down all the procedures in our tests. It was she who studied the results and got the record exact to the last comma. In reading this book bear in mind, there are no errors. If the book says that the experiment was done in a certain precise way, that is the way it was done; and always it was done without prejudice, without a preconception or anything that could affect the result. When the record was put on paper every word had to be studied, and every little mistake that I made had to be corrected by her tenacious memory.