"... we have decided to publish what is printed of Principia Mathematica at once in a thin volume (about 480 pages), and I have had to make the table of contents and list of errata—such things as 'p. 218, last line but one, for — read —', where only a very careful reader would notice there was any change. But although it is tedious it is soothing; work that involves no thought is always rather agreeable. What remains to be done to the book is Whitehead's affair—his ms. won't be ready till the autumn at the earliest.

[Letter no. is not on letter.]