Darwin’s notebooks provide an invaluable record of his scientific thinking and most importantly, the development of his theory of natural selection. This edition of the notebooks, prepared to the highest standard of textual editing, thus affords a unified view of Darwin’s professional interests. The Red Notebook, used on the voyage of H. M. S. Beagle and afterwards in England, contains Darwin’s first evolutionary statements. In July of 1837, Darwin began his ‘Transmutation Notebooks’ (B - E) devoted to the solution of the species problem and in the third notebook of this series he first formulated the theory of natural selection. This volume also contains Notebook A and the glen Roy Notebook on geology, Notebooks M and N on man and behaviour and a notebook labelled Questions and Experiments. Fresh transcriptions have been done for all previously published manuscripts, with readings made directly from Notebooks B, C, D and E, presenting them with previously excised pages and restored to their original sequence.