5 But what means, “who alone does great wonders”? Is it because many wonderful things He has done by means of angels and men? Some wonderful things there are which God does alone, and these he enumerates, saying, “who by His wisdom made the heavens”, “who stretched out the earth above the waters”, “who alone made great lights”. For this reason did he add “alone” in this verse also, because the other wonders which he is about to tell of, God did by means of man. For having said, “who alone made great lights,” he goes on to explain what these are, “the sun to rule the day”, “the moon and stars to govern the night”; then he begins to tell the wonders which He did by means of angels and men: “who smote Egypt with their first-born”, and the rest. The whole creation then God manifestly made, not by means of any creature, but “alone;” and of this creation he has mentioned certain more eminent parts, that they might make us think on the whole; the heavens we can understand, and the earth we see. And as there are visible heavens too, by mentioning the lights in them, he has bid us look on the whole body of the heavens as made by Him.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)