The Rule of the Carthusian Order, founded towards the close of the eleventh century by St. Bruno, was of such extreme austerity, and was so persistently adhered to down to the fifteenth century, at least, that we need not wonder to find no vestiges of buildings erected by this community contemporaneously with those of other great foundations. The Carthusians clung longer than any of their brethren to the vows of poverty and humility which obliged them to live like anchorites, though dwelling under one roof. Far from living in common, on the cenobitic method, after the manner of the Benedictines and Cistercians, they maintained the cellular system in all its severity. Absolute silence further aggravated the complete isolation which encouraged them to scorn all that might alleviate or modify the rigours of their religious duties. In time, however, the Carthusians relaxed something of this extreme asceticism in their monastic buildings, if not in their religious observances. Towards the fifteenth century they did homage to art by the construction of monasteries which, though falling short of the Cistercian monuments in magnificence, are of much interest from their peculiarities of arrangement. The ordinary buildings comprised the gate-house, giving access by a single door to the courtyard of the monastery, where stood the church, the prior's lodging, the hostelry for guests and pilgrims, the laundry, the bakehouse, the cattle sheds, storerooms, and dovecote. The church communicated with an interior cloister, giving access to the chapter-house and refectory, which latter were only open to the monks at certain annual festivals. The typical feature of St. Bruno's more characteristic monasteries is the great cloister, on the true Carthusian model--that is to say, rectangular in form, and surrounded by an arcade, on which the cells of the monks open. Each of these cells was a little self-contained habitation, and had its own garden. The door of each cell was provided with a wicket, through which a lay brother passed the slender meal of the Carthusian who was forbidden to communicate with his fellows. The Rule of St. Bruno, as is commonly known, enjoins the life of an anchorite; the Carthusian must work, eat, and drink in solitude; speech is interdicted; on meeting, the brethren are commanded to salute each other in silence; they assemble only in church for certain services prescribed by the Rule, and their meals, none too numerous at any time, were only taken in common on certain days in the year. The severity of these conditions explains the extreme austerity of Carthusian architecture. It had, as we have already said, no real development until the fifteenth century, and then only as regards certain portions of the monastery, such as the church and its cloister, which were in strong contrast with the compulsory bareness of the great cloister of the monks.