misunderstood; his motives will be called in question; among those for
whom he is chiefly working he will find indifference. Indeed, the pioneer
in this field may well count himself happy if he meets with nothing worse
than indifference. Hence it is that the present volume will not be
published in England, but that, availing myself of the generous sympathy
with which my work has been received in America, I have sought the wider
medical and scientific audience of the United States. In matters of faith,
"liberty of prophesying" was centuries since eloquently vindicated for
Englishmen; the liberty of investigating facts is still called in
question, under one pretence or another, and to seek out the most vital
facts of life is still in England a perilous task.

I desire most heartily to thank the numerous friends and correspondents,
some living in remote parts of the world, who have freely assisted me in
my work with valuable information and personal histories. To Mr. F.H.
Perry-Coste I owe an appendix which is by far the most elaborate attempt
yet made to find evidence of periodicity in the spontaneous sexual
manifestations of sleep; my debts to various medical and other
correspondents are duly stated in the text. To many women friends and
correspondents I may here express my gratitude for the manner in which
they have furnished me with intimate personal records, and for the
cross-examination to which they have allowed me to subject them. I may
already say here, what I shall have occasion to say more emphatically in
subsequent volumes, that without the assistance I have received from women
of fine intelligence and high character my work would be impossible. I
regret that I cannot make my thanks more specific.

HAVELOCK ELLIS.