I am very pleased that my books about David Hilbert, published in 1970, and Richard Courant, published in 1976, are now being issued by Springer- Verlag in a single volume. I have always felt that they belonged together, Courant being, as I have written, the natural and necessary sequel to Hilbert- the rest of the story. To make the two volumes more compatible when published as one, we have combined and brought up to date the indexes of names and...