3. In the tenth century there was a very general belief that the world was coming to an end at the end of the thousand years after the establishment of Christianity; so there was not much actual church-building going on. But in King Cnut's time a revival of interest in church-building took place, and there are in a good many of the old churches of England little bits of work in the walls, or very rude carvings over the doorways, which belong to this time. Unless such work is pointed out to you by one who understands something about these matters, you will not be likely to discover it for yourself, any more than you are likely to discover the traces of the pit-dwellings, of which we spoke in an early chapter. 4. These parish churches and parish priests were under the control of the bishop, who had his chief church or =cathedral= in some important place in his diocese. Those cathedrals were generally served by colleges of clergy, called canons. 5. These were the =public churches=. But besides them there were colleges and monasteries, which were =private societies= of men living together. Some of the religious houses were in towns, as we have seen, and others were in wild desolate places. Every religious house, whether a monastery for men or a nunnery for women, had its church, which was the private chapel of the house, and not open to the public. In the course of years these private chapels were built as huge churches, much larger than the parish church. Even now you may see close to a big college church a much smaller parish church, as for example St. Margaret's Church, which stands by the side of Westminster Abbey. As more land came into the possession of these religious houses, the monks had more business with the outside world, for, as landlords, they had to see that their lands were turned to good account, and cultivated according to the notions of the day. 6. The monasteries, especially in their early days, were great centres of good and useful work. Those who founded them, or gave them lands, did so because they felt they were doing excellent service for the people, and they wanted to have a share in the work, and to be remembered in the prayers of the monks. Founders of religious houses believed that they were getting something worth having in return for the lands which they gave. 7. In the wild times of the Danish invasions the monasteries were looked upon as places of safety for the weak and helpless. But they were not always safe places. People sometimes, when the country was in a disturbed state, would send their valuables to the nearest monastery. In time the Danes got to know of this, and many a religious house was attacked and sacked by them on account of the tales they had heard of the marvellous wealth hidden there.