GOD KNOWS HIS OWN
The guillemot is a small arctic sea bird that lives on the rocky cliffs of northern coastal regions. These birds flock together by the thousands in comparatively small areas. Because of the crowded conditions, hundreds of females lay their pear-shaped eggs side by side on a narrow ledge in a long row. Since the eggs all look alike, it is incredible that a mother bird can identify those that belong to her. Yet studies show that she knows her own eggs so well that when even one is moved, she finds it and returns it to its original location.
Scripture tells us that God is also intimately acquainted with each of his children. He knows our every thought and emotion, every decision we must make and problem we are going through. Therefore, an understanding (of the full extent) of God's omniscience should both evoke praise and bring comfort to believers.
(SOURCE: Green, M. P. (1989). Illustrations for Biblical Preaching : Over 1500 sermon illustrations arranged by topic and indexed exhaustively (Revised edition of: The expositor's illustration file). Grand Rapids: Baker Book House.)
(from a sermon by Matthew Kratz, "God is Omniscient" 7/5/08, SermonCentral.com)