This book has been some years in the making and would never have been completed without the generous support of institutions and individuals. The Research Lectureship I held at Christ Church, Oxford from 1974–8 enabled me to lay a solid foundation for it in the most congenial and stimulating of environments. Research in Spain and Portugal was made possible by the award of a Denyer and Johnson Travelling Fellowship by the Faculty of Theology in Oxford in 1977, and by a subsequent grant from the British Academy.

I shall not forget the friendship and hospitality of the Augustinian communities which received me in Madrid, Salamanca and El Escorial, and I am deeply grateful to the Provincial, Father Vicente Gómez Mier, OSA, for inviting a Reformed minister to live and work in the Escorial, the heart of Counter-Reformation Spain. Nor shall I forget the courtesy of Father José Goñi Gaztambide of Pamplona Cathedral and of others like him, who allowed me to consult precious manuscripts and to work on undisturbed.

I should especially like to express my gratitude to Dr R.W. Truman of Christ Church and to Professor Peter Russell for their unfailing encouragement and many valuable suggestions, and to Eric South-worth of St Peter's College, Oxford for the help he has given me in revising and improving my drafts. I am also very grateful to Fr Bruce Harbert, Roman Catholic Chaplain at the University of Sussex, for his help with the translation of the Latin quotations.