[Illustration: ANCIENT IRELAND, shewing the Ancient Schools and Principal Territorial Divisions before the Anglo-Norman Invasion. _Sealy, Bryers & Walker, Lith., Dublin._] INSULA SANCTORUM ET DOCTORUM OR, IRELAND'S ANCIENT SCHOOLS AND SCHOLARS BY THE MOST REV. JOHN HEALY, D.D., LL.D., M.R.I.A., BISHOP OF CLONFERT; COMMISSIONER FOR THE PUBLICATION OF THE BREHON LAWS; EX-PREFECT OF THE DUNBOYNE ESTABLISHMENT, MAYNOOTH COLLEGE. SIXTH EDITION. DUBLIN: SEALY, BRYERS & WALKER, 86 MIDDLE ABBEY STREET. M. H. GILL & SON, 50 UPPER O'CONNELL STREET. LONDON: BURNS & OATES, LIMITED, 28 ORCHARD STREET, W., AND 63 PATERNOSTER ROW, E.C.. NEW YORK, CINCINNATI AND CHICAGO: BENZIGER BROTHERS. 1912. PRINTED BY SEALY, BRYERS AND WALKER, MIDDLE ABBEY STREET, DUBLIN. PREFACE TO THE FOURTH EDITION. Some smaller inaccuracies in the previous Editions have been corrected in this Edition; but no other changes have been made. ✠ JOHN HEALY, D.D., Bishop of Clonfert. MOUNT ST. BERNARD, _October, 1902_. PREFACE TO THE SECOND EDITION. The FIRST EDITION of this work has been very favourably received both by the critics and by the public. It was exhausted nearly twelve months ago; but other engrossing occupations left the author little time to revise the text and prepare a new edition. In this SECOND EDITION many errors of the press have been corrected; several explanatory notes have been added, and some few inaccuracies have been rectified. Maps of the Aran Islands and Clonmacnoise have been inserted, and the _Index_ has been greatly enlarged. It is hoped also, that the lower price of the present edition will bring it within the range of a wider circle of readers, and still further carry out the author's purpose of vindicating and enlarging the just renown of Ireland's ancient Saints and Scholars. ✠ JOHN HEALY, D.D. MOUNT ST. BERNARD, _Easter, 1893_. PREFACE.