Sourcery topic

Sourcery is the fifth Discworld novel by Terry Pratchett, published in 1988. On the Discworld, sourcerers - wizards who are sources of magic – were the main cause of the great mage wars that left areas of the disc uninhabitable. Men born the eighth son of an eighth son are commonly wizards. Since sourcerers are born the eighth son of an eighth son of an eighth son, wizards are not allowed to marry or have children. The first few pages of the novel deal with a sourcerer's father who cheats death... full article at wikipedia