The structure of these early monasteries was of a simple and inexpensive character. Like the early Celtic churches, they were built at first of earth, wattles, or wood. It was not until the eighth century that stone buildings began to be substituted for wooden ones, as a protection against the ravages of the Danes.[165] The simplicity and temporary character of these early foundations would account for the quickness with which monastic cities sprang up as well as for the fact that comparatively few material remains of these monastic settlements are now to be seen. They are now remembered chiefly for the great spiritual and literary heritage which they were the means of transmitting.
They were of various sizes. Those planted on barren islands off the coast of Ireland and Scotland must have been small. In each of the great monasteries of Clonard, Bangor and Clonfert there were 3000, including probably both monks and students. St. Molaise had 1,500 at Mungret, St. Gobban had 1000 and so on down to the school of St. Mobi at Glasnevin with 50. This last number, fifty, seems to have been the usual number in the smaller monastic schools.[166]
The investigations of scholars in recent years brought to light several Rules[167] which were written by early Irish saints for the direction and guidance of their monks. These Rules were frequently referred to in ancient documents, but some historians doubted their existence until their discovery set all doubts aside and furnished another proof of the trustworthiness of Irish records. By comparing these Rules with the references in the _Lives of the (Irish) Saints_[168] to the domestic and religious discipline of the monks we are able to form a tolerably correct picture of the real character of monastic life in Ireland during the period under consideration. While these Rules are neither so elaborate nor so systematic as the famous _Rule of St. Benedict_, to which they eventually gave place, yet they enable us to realize the austere simplicity of Irish monasticism.
However they may differ in details these “Rules of the Irish Saints” are in agreement as to the character of the daily work. St. Columbanus thus tersely describes the work of an Irish monastery: “Ergo quotidie jejunandum est, sicut quotidie orandum est, quotidie laborandum, quotidie est legendum.”[169] Fasting and prayer, labour and study were the daily task of the monk in every Irish monastery.