Having taken the Upanishad as the bow, as the great weapon, let him place on it the arrow, sharpened by devotion! Then having drawn it with a thought directed to that which is, hit the mark, O friend, viz. that which is the Indestructible!

In plain words: The teaching is like a mighty bow. Put on it an arrow made sharp by devotion. Then draw it back with your mind fixed on what is real, and hit the target, which is the Indestructible.