Yi Ik had been born in 1681. He is one of the Pragmatists in Yi Dynasty. Generally speeking, the outline of the characteristics of his doctrines are as follows:
1) Alike Ban'gye, Yu Hyong-Won 반계 유형원, he says "agriculture is the fundamental industry(occupation) in the world and all of the other economic activities, except agriculture, are branch." In this point they are same Physiocrats. But, Yi Ik, is an estream Physiocrat. For instance, Yi Ik says "handicraft is a noxious insect to nation, because, as the handicraft is very profitable than agriculture, farmers abandon their farms and run to handicraft, as the result, the fundamental industry, agriculture, must be declined in prosperity. Government must keep farmers apart from profit."
2) He says money(coin) is a noxious insect to nation, because, (a) coin increase the propensity to consume and people are apt to indulge in luxury, (b) as coin is light and convenient to carry, thiefs will rampant." He is very conservative as compare with Yu Hyong-won. In spite of about 60 years senior to Yi Ik, Yu Hyong-won ardently recommended the use of coin.
3) Yi Ik disliked extremely the foreign trade. In his age, as the trade between Korea and China brought the excess of import over export, silver flew into China as the price of consumptive goods. Therefore, he asserted that watchmen must be stationed in frontier in order to prohibit the trade. When we compare his doctrines with Mercantilism, we find a very interesting point. Early Mercantilism acquired gold and silver by foreign trade with feverish eyes positively, Yi Ik wanted to protect silver negatively by checking foreign trade.
4) Yi Ik is an extreme stoic. He says "if any farmer is so poor that he is not able to take three meals a day, take two meals, if so poor that cannot take two meals a day, take only vegetable. The force of hibit makes man quite inured to it." As the example he shows us the hibernation of animals. Another interesting point of his opinion is sex problem. He says "in animal world they do not choose their spouse by beauty or plainness of face, but, humankind choose by beauty, in this point human is inferior to animal."
5) He denounced Korean slavely. He is an ardent abolitionist. In this point he is progressive than Tasan, Chong Yag-yong다산 정약용. Chung Yag-yong opposed stubbornly the abolition of slaves.
6) He condemned the Kwago System과거(the Higher Civil Service Examination) as a noxious insect to nation because of two reasons. The one is unfairness and the other is the exploitation of farmers and despite of labor in the life-long of the successful candidates.
Summarizing, his fundamental thought is an assertion that Korea should keep an ablockaded self-sufficient economy eternally only by encourage of agriculture without any other industry and foreign trade. But, in this point, Chongyu, Pak Che-ga 박제가 is the most progressive scholar among the pragmatists in Yi Dynasty, he asserted foreign trade ardently.