I2 INTRODUCTIONtrary.9 This idea has been further explored recently by Yi Usong and Kim
Chunsok, who have studied the recently published collection of his writings on
miscellaneous issues and other materials. IO Yi found in a letter Yu wrote to Chang
Tongjik at the age of thirty-seven se that he was inclined to favor the notion that
psycho-physical energy took primacy over principle because he could not
imagine how principle could even exist in the absence of psycho-physical energy
since principle had no materiality to it. A decade later, however, at the age of
forty-eight se he changed his mind and declared that both principle and psycho-
physical energy existed together and were intermixed with one another, and that
principle did not owe its existence to psycho-physical energy.
He rejected Yulgok's view that principle and psycho-physical energy "issued
forth" or made their appearance jointly. He preferred to think of the "mind of
Heaven" (ch onsim, the equivalent of principle in the world) as always a part of
"the mind of man" (insim, the equivalent of the imperfect human mind beclouded
by the psycho-physical energy within it) and never separated from it. But this
did not mean that he automatically adopted that position because he had decided
to follow T'oegye. On the contrary, he also thought that T'oegye's perception of
the igi relationship, that "when principle emerges, psycho-physical energy fol-
lows it, and when psycho-physical energy emerges, principle rides on it" was
too suggestive of dualism, connoting the possibility of separation between moral
principles and the inert materiality in which it inheres.
Instead, he worked out his own formulation, that principle and psycho-phys-
ical energy were "never separated" and that principle, or moral principles, often
referred to as the "mind of the Way" (tosim, equivalent to the mind of Heaven)
was also to be found in the mind of man, which was vulnerable to human desire
and corruption. Yi Usong suggested that he probably received some inspiration
for this viewpoint from the first important statecraft scholar of the seventeenth
century, Han Paekkyom. Han's essay on "The Four Origins and Seven Emo-
tions" (sadan ch'ilchOng), rejected Yulgok's view that moral principles in the
mind (the four origins) were produced by the mind of Heaven, while the source
of the seven emotions (i.e., impure feelings and desires rather than pure virtue)
was the mind of man. Han's correction to this formulation was that psycho-phys-
ical energy was responsible for the emergence (of both), but that principle was
to be understood as the reason why anything (i.e., psycho-physical energy)
emerged or appeared in the world at all - a position that at once refuted both
Yulgok's and T'oegye's positions.
Yu reinforced his preference for principle by making the conventional argu-
ment that principle was to be found in everything in the universe, but he empha-
sized not only things and events, but in particular the laws and institutions of
the real world, which he had chosen to be the objects of his own study. He called
his version of principle, "real principle" (sill i), and the object of his study "real
facts" (silsa). Yi Usong wrote that Yu's shift to a position close to principle-
monism meant that his objective was now to determine what Heaven's princi-