The internal testimony of the Holy Spirit is a heart-rooted conviction that Scripture is the authoritative Word of God. Similarly, the continuing process of biblical interpretation in the process of sanctification should aim also at heart-understanding. Interpretation of Scripture involves much more than head-knowledge or the gaining of information, historical or other. That is why illumination is a continuing need.—Klooster, "The Role of the Holy Spirit in the Hermeneutical Process," in Hermeneutics, Inerrancy, and the Bible, ed. by Radmacher and Preus (Zondervan, 1984), 461-62.
Illumination of the HS when the believer reads the Scriptures, part II
So here is another excellent quote from Fred Klooster on the illumination of the Holy Spirit and how it is inextricably tied with heart-understanding. Read it, and then read it again to make certain you didn't omit anything: