A comparison of leading Sillhak실학(Pragmatic School of the Yi Dynasty) literati from Yu Hyong-won유형원 down to Yi Ik이익, Pak, Chi-won and Pak Che-ga박제가 gives us the impression that those literati of early generations were concerned with large-scale economic policy, while those of later generations placed emphasis on actual technical aspects. To be sure, some of the literati of later generations were concerned with not only actual techinical aspects but also economic policy. Good examples are Pak Che-ga and Pak Chi-won. Besides his technological argument, Pak Che-ga presented an argument on economic policy in which he emphasized the need of encouraging commerce and trade with foreign countries. On the other hand, Pak Chi-won fervently insisted upon the enforcement of public land system so as to prevent the dispossession of land, the prohibition of the selling of land after confirming the size of land under holding, and the rationalization of farming. These were all outstanding arguments on economic policy at that time. Also, it should be noted that Pak Chi-won as well as Yu Hyong-won advocated the reform of the Kyolbu결부 system and stressed freeing the peasantry from all kinds of miscellaneous taxation.
However, Pak Chi-won, together with Pak Che-ga, was far more thoroughgoing in his argument for reform of techniques on actual management of agriculture. His Kwanong Soch'o과농 소초 consists of various items, such as land system, agricultural instruments, farming, manuring, irrigation, the selection of seeds, seeding, the maintenance of spades, harvesting, cattle raising, and the distribution of land; of these items, only the first and last items deal with policy, and all the rest deal with actual techniques on agricultural instruments, explaining their shapes and utilities, and advocates the adoption of those instruments in Korea. He even produced some of them for himself, and attempts the adoption of those instruments in Korea. He even produced some of them for himself, and attempted to demonstrate their superior qualities in front of farmers. As regards irrigation, he gives the concrete method of embankment; in farming, he gives accounts for the appropriate time and method of tilling. Under the item Seeding, every sort of edible grain seeds is listed, the method of selecting good seeds being indicated; at the same time, he emphasizes the adaptability of seeds to a given soil and timely seeding.
Then why did he(and Pak Che-ga) place special emphasis on actual agricultural techniques like this? The reasons for this are as follows. First, since Yu Hyong-won(and Yi Ik) was the originator of the Sillhak School, it was natural that the he should realize the acute need of reforming, before everything else, the morbid system of long standing rather than actual technical problems. The industry of the Yi Dynasty, except agriculture, was insignificant; therefore, the Silhak literati of later generations could find nothing new to add to the views of Yu Hyong-won and Yi Ik on agricultural policy. Second, Yu Hyong-won and Yi Ik, who had never been to china, had no chance to witness various factors of the Chinese civilization with their own eyes. In contrast with them, Pak Chi-won(and Pak Che-ga) visited China several times when the Ch'ing Dynasty was at the zenith of prosperity. Witnessing various convenient farming tools and efficient farming techniques employed in China, Pak Chi-won was surprised at the gap of quality in the agricultural line between Korea and China. The consciousness of this gap was more keen in the case of Pak Che-ga, as we can not in his Pukhagui북학의, in which he expresses his indignation at the disdainful attitude of ruling Korean literati toward the Ch'ing Dynasty. Thus, Pak Chi-won and Pak Che-ga ardently advocated the introduction and wide use of various kinds of farming tools and techniques of superior quality in Korea.
Viewed in this light, it can be said that the reefs of thought of Pak Chi-won and Pak Che-ga are less extensive than those of Yu Hyong-won and Yi Ik.