The Spanish government applied its restrictive colonial system with the utmost rigour. The obnoxious market tax was imposed as early as 1690; tobacco and salt were made monopolies; the exportation of agricultural products was discouraged; and the production of gold, emeralds, platinum, and silver, was jealously watched and heavily taxed. In the early history of the colony the profits of mining were prodigious, but during the seventeenth century, after the cream of the surface placers had been skimmed, progress was slow. The unhealthful climate of the mining regions almost exterminated the settlers; the native population diminished so rapidly that soon the mines were short-handed; and the importation of negro slaves was so costly that the smaller proprietors could not operate on their own account, and even the great mine owners had to be content with moderate profits. One-fifth of the gross product was required to be paid to the government, and there were other fiscal exactions. The efforts of the authorities to prevent the smuggling of gold introduced a swarm of soldiers, collectors, and guards with whom the miners were in a constant turmoil. The influence of the Church was very powerful, and the population became devotedly Catholic. Great tracts of the best lands were given to the bishoprics and the religious orders. Piously disposed persons left property in trust charged with the payment of so many dollars a year for the saying of so many masses, and the stewardships, or rights to administer these estates, were the subject of sale or descended from father to son. In 1630, a daring president, Jiron, presumed to arrest and banish the archbishop of Bogota, but fifty years later one of his successors wrote back to Spain that "in New Granada there is much Church and little king." The poor Indians were decimated not only by war, massacre, and forced labour in the mines, but the white man's diseases played havoc with them. The small-pox was introduced on the plateaux within a few years after the conquest, and continued to ravage the country throughout the early part of the seventeenth century. The third president died of the leprosy within a few months after his arrival in 1579, and the first case of elephantiasis, which has proved a curse to Colombia, occurred in 1646.