"which they do not even suspect to be in the Bible will be made manifest. All who walk in the path of humble obedience, fulfilling His purpose, will know more and more of the oracles of God. MH 465.2"
"If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself."
Both passages connect obedience to God's will with increased understanding of divine truth. The EGW passage expands on the principle found in John 7:17, making the connection genuine and meaningful.
"Let the student take the Bible as his guide and stand firm for principle, and he may aspire to any height of attainment. All the philosophies of human nature have led to confusion and shame when God has not been recognized as all in all. But the precious faith inspired of God imparts strength and nobility of character. As His goodness, His mercy, and His love are dwelt upon, clearer and still clearer will be the perception of truth; higher, holier, the desire for purity of heart and clearness of thought. The soul dwelling in the pure atmosphere of holy thought is transformed by intercourse with God through the study of His word. Truth is so large, so far- reaching, so deep, so broad, that self is lost sight of. The heart is softened and subdued into humility, kindness, and love. MH 465.3"
"Keep thy heart with all diligence; for out of it are the issues of life."
While not a direct quote, the EGW passage echoes the sentiment of Proverbs 4:23 about guarding the heart and its impact on life, expanding on the idea of the heart's influence on character and perception of truth.