The greatest hindrance to knowledge is our adjustment to conventional, to mental cliches. Wonder or radical amazement, the state of maladjustment to words and notions is, therefore, a prerequisite for an authentic awareness of that which is. Rabbi Abraham Joshua Heschel, Man Is Not Alone.
Scholars have long struggled to understand just what the heart (lev) symbolizes in biblical thinking. Some interpreters insist that in the Torah, the heart is "considered, not the seat of feelings, but of intelligence," in which case what the Torah asks for in our verse is for Israel to open its mind. Others assert that is is "the organ of volition" in which case what is called for is a conversion of the will. More convincing, in my view, is a more expansive interpretation, according to which "the heart in Hebrew thought is the preeminent metaphor for the inner being of a person, the seat of intelligence; the seat of emotions, and the seat of volition, i.e., the will." Moses thus demands that the people totally transform their inner lives, so that they will now respond to God's command with loyalty, readiness, and faithfulness. As Bible scholar Richard Nelson explains, "circumcising the heart is a metaphor for a radical, interior, renewal that makes love and obedience fully possible." Rabbi Shai Held; Will and Grace Or: Who Will Circumcise the Heart