{In his heart} (en t(8869) kardi(8369) autou). Not just the centre
of the blood circulation though it means that. Not just the
emotional part of man's nature, but here the inner man including
the intellect, the affections, the will. This word is exceedingly
common in the New Testament and repays careful study always. It
is from a root that means to quiver or palpitate. Jesus locates
adultery in the eye and heart before the outward act. Wunsche
(_Beitrage_) quotes two pertinent rabbinical sayings as
translated by Bruce: "The eye and the heart are the two brokers
of sin." "Passions lodge only in him who sees." Hence the peril
of lewd pictures and plays to the pure.