My chief feeling on finishing this book is one of gratitude. I have been helped by many librarians, scholars and students. The staff of the manuscripts department at the Bodleian Library made my frequent visits to Oxford both productive and pleasurable; and for permission to quote from the correspondence of J. L. and Barbara Hammond held there I am indebted to Professor N. G. L. Hammond. Miss Angela Raspin greatly facilitated my work at the London School of Economics, especially on an unexplored section of the Wallas papers and on the manuscript of Beatrice Webb's diaries; I am likewise grateful for permission to quote from these sources. Mrs Jennifer Balme showed great consideration in making some of the surviving papers of her grandfather, L. T. Hobhouse, available to me. I am also grateful to Mr S. S. Wilson for allowing me to use the minute books of the Rainbow Circle. My colleague Melvyn Stokes generously let me partake of the fruits of his own labours in the archives of American progressives; and Mary Chadwick expeditiously extracted the material in the appendix from the probate records at Somerset House. Professors Norman Mackenzie and J. H. Burns commented on early parts of the manuscript to my great benefit. Above all, I am conscious of the help of those friends whom I implicated in the preparation of the final draft. Without Nazneen Razwi, who typed it, the work could not have been finished at all.