Lee Gu(李榘, 1613~1654, 活齋) was a genuine confucian scholar who did not take a public office in the first half of the 17th century. He was a representative Nam-in(南人) confucian intellectual who was called Sanyangchosa(山陽處士) in Sang-ju district. In those days So-in(西人) was more predominant in Sang-ju. He respected Ju-hee and Lee-hwang, therefore took an active part in the advocating neo-confucian theory(性理說) of Lee-Hwang through various writing activities. But he minutely criticized the theory of Lee-i who was the leader of So-in. In this respect he played a leading role to criticize Lee-i's theory by his systematic Xing-li theory. In addition he appealed against memorial rite ceremony for Sung-hon and Lee-i and sent a letter of plea to king. In the basis of realizing the situation he completed his duty in the challenging condition, but he passed away at the age of 42 and was held a memorial service for him at Gunam-Sowon(近癌書院) in Mun-Keong.
Lee-gu has not lived long, so did not make disciples and wise sons. He did not established a firm foothold in Yeong-nam, too. Nevertheless he was admired by Yeong-nam Nam-in for a long time. And his various writings were read and studied by intellectuals, in that regard he was quite a more influential person in Nam-in than known. It is because he has his writings'power, academic legacy, and respectable personality. If he lives a long life, he changes academic topographic map in Nam-in remarkably.