Another interpretation of "Who has split a channel for the flood" (Job 38:25): When the Holy One, blessed be He, created the human, He created him with wisdom. How so? Had He created him mostly water and a little blood, he would have become an istenis (a frail, fastidious person); had He created him mostly blood and a little water, he would have become a leper. Half water and half blood — [behold, this is] a whole human.
How God Balanced Water and Blood to Form a Whole Human
Midrash Tanchuma Buber, Tazria 8:2
ד"א מי פלג לשטף תעלה. כשהקב"ה ברא את האדם בחכמה ברא אותו, כיצד אם ברא אותו רובו מים ומיעוטו דם, נעשה איסטניס, אם ברא אותו רובו דם ומיעוטו מים, נעשה מצורע, חציו מים וחציו דם [הרי זה] אדם שלם.