In what way "Tamshilehu b'Ma'asei Yadecha"?
Radak #1: He rules over the lower creations.
Radak #2: He rules even over the higher creations. His 'authority' is that he understands with his intellect the movement of the spheres and stars.
Malbim: This is the third proof that man is the purpose of creation. Man is a microcosm of the world. All laws seen in the creation are found in man. He is the Mashal and semblance of the entire larger world. The relation of the other creations to man is like the part to the whole, and the individual to the Klal.
Why does it say "Kol Shatah Sachas Raglav"?
Shocher Tov: This refers to David. All his enemies fell under him - "v'Eschakem ka'Afar Aretz" (Shmuel II, 22:43).
Radak: All lower beings are under [man] - "u'Mora'achem v'Chitechem Yihyu Al Kol Chayas ha'Aretz
