THE nucleus of this book was presented as a thesis for a Doctorate
of Philosophy in the National University of Ireland and I am
deeply grateful to the Senate of the University for generous
financial aid towards the publication of the book.

The Reverend Professor A. Gwynn, S.J., Professor of Medieval
History at University College, Dublin, and Professor E. F.
Jacob, Chichele Professor of Modern History in the University of
Oxford, have given invaluable advice and criticism at every stage
of the book's composition and it is chiefly due to their encourage-
ment that I have been able to complete this study of one aspect of
Gerson's many-sided career. I am also much indebted to Monsig-
nor P. Glorieux, Rector of the Catholic University of Lille;
G. R. Potter, Professor of History at the University of Sheffield,
and Dr. Z. Rueger of the University of London for so freely
placing their own knowledge of Gersonian problems at my
disposal on specific points. Professor Potter's kindness extended to
a generous long-term loan of a number of rare printed sources and
I am particularly grateful to him for thus facilitating my work.

Last but not least my best thanks are due to the Committee
of the Manchester University Press for undertaking the publica-
tion of the book and to Mr. T. L. Jones, B.A., Secretary of the
Press, for his ever-ready practical help.

J. B. M.

UNIVERSITY COLLEGE,
DUBLIN
February, 1959

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