But the advances, or rather retrogressions, in a Buddhistic line were still more marked. In 1065 the King’s son Ku cut his hair and became a monk. A law was promulgated that no beast should be killed in the land for three years. A monastery was being built in Song-do containing 2,800 _kan_, each _kan_ being eight feet square. It took twelve years to complete it. When it became ready for occupancy there was a magnificent festival at which all monks within a radius of many miles were present. The feasting lasted five days. There was an awning of silk, covering a passage-way from the palace to this monastery. Mountains and trees were represented by lanterns massed together. The King dressed in the robes of a high priest. In this monastery was a pagoda on which 140 pounds of gold and 427 pounds of silver were lavished. Chapter IV. Revenue.... mathematics.... the bridge removed.... friends with China again.... Confucianism wanes.... Buddhist book from Japan.... frontier defence.... prophecy.... Han-yang made a secondary capital.... new laws.... cash counterfeited.... Yŭ-jin taken.... botany.... beginnings of the Kin power.... between Kitan and Kin.... kingdom of Wŭn.... China allies herself with Kitan.... Kin seeks the good will of Koryŭ.... dancing-girls and Buddhism.... Kin demands Koryŭ alliance.... refused.... defense of the north.... an ambitious official.... Kitan falls.... Sung dynasty falls.... harbor improvement.... Buddhist trickery.... rebellion quelled.... historical work, Sam-guk-sa.... an abject king.... Kin immigrants.... a good governor for Quelpart.... military faction dominant.... criminals, houses destroyed.... king banished.... a plot foiled.... the emperor suspicious.... military and monastic factions.... attempted revolution.... monastic revolt. It is evident that population and revenue are proportionate. Not often is the question of population touched upon in the Korean annals but some light is thrown upon it by the statement that at this time the revenue from the north, from the most distant places only, was 49,000 bags of rice. From this we must infer that the north was fairly well populated. An interesting point in connection with the mathematical knowledge of the time is brought out in the statement that the system of land tax was changed and was collected at a certain rate per each square of thirty-three paces; but if the field was large the tax was a certain amount for each tract forty-seven paces square. The square of thirty-three is 1089 and the square of forty-seven is 2209, which is the nearest possible to twice the square of thirty-three. It would seem then that they had some notion of the properties of geometrical figures.