The Mekhilta draws a sharp contrast between human construction and divine creation. When a human being builds, the natural order is bottom-up. You lay the foundation first, then build the walls, then raise the roof. The lower structure supports the higher. This is not just architectural convention. It is physical necessity. Without a foundation, nothing stands.
God works differently. (Genesis 1:1) states: "In the beginning God created the heavens and the earth." The heavens come first. The earth comes second. God built from the top down, creating the higher before the lower, the roof before the floor.
The Mekhilta calls this "the measure of flesh and blood" versus the measure of the Holy One Blessed be He. Human beings are bound by physical constraints. They must work with gravity, with weight, with the limitations of material. God is bound by nothing. He creates the sky before the ground because He does not need a foundation. His creation does not require structural support. It holds because He wills it to hold.
This observation does more than note an interesting detail in the creation narrative. It establishes a fundamental theological principle: God's methods are not simply superior versions of human methods. They are categorically different. Humans build up from the earth because they are creatures of the earth. God begins with the heavens because He is the God of the heavens. The order of creation reveals the nature of the Creator.
The Mekhilta uses this contrast to remind its readers that analogies between human and divine action always break down at some point. God is not a bigger, stronger builder. He is a fundamentally different kind of creator.