The urgent need for a collection of the more important of these documents in English translation was the reason for initiating the project which has now culminated in the publication of this volume. The translators invited to do the work are competent Latent and Greek scholars who have also manifested their proficiency in theological learning. Although the work has bees checked and re-checked, we would be very grateful for any forthcoming suggestions for improving either the translations themselves or the selection of the documents used.