The prohibition to eat blood is repeated in seven places in the Pentateuch, but in this passage two distinct grounds are given for the prohibition: first, its own nature as the vital fluid; secondly, its consecration in sacrificial worship.
Rather, For the soul of the flesh is in the blood; and I have ordained it for you upon the altar, to make atonement for your souls, for the blood it is which makes atonement by means of the soul. In the Old Testament there are three words relating to the constitution of man;
(a) “life” as opposed to death Genesis 1:20; Deuteronomy 30:15;
(b) the “soul” as distinguished from the body; the individual life either in man or beast, whether united to the body during life, or separated from the body after death (compare Genesis 2:7);
(c) the “spirit” as opposed to the flesh Romans 8:6, and as distinguished from the life of the flesh; the highest element in man; that which, in its true condition, holds communion with God. The soul has its abode in the blood as long as life lasts. In Leviticus 17:14, the soul is identified with the blood, as it is in Genesis 9:4; Deuteronomy 12:23. That the blood is rightly thus distinguished from all other constituents of the body is acknowledged by the highest authorities in physiology.
“It is the fountain of life (says Harvey), the first to live, and the last to die, and the primary seat of the animal soul; it lives and is nourished of itself, and by no other part of the human body.” John Hunter inferred that it is the seat of life, because all the parts of the frame are formed and nourished from it. “And if (says he) it has not life previous to this operation, it must then acquire it in the act of forming: for we all give our assent to the existence of life in the parts when once formed.” Milne Edwards observes that, “if an animal be bled until it falls into a state of syncope, and the further loss of blood is not prevented, all muscular motion quickly ceases, respiration is suspended, the heart pauses from its action, life is no longer manifested by any outward sign, and death soon becomes inevitable; but if, in this state, the blood of another animal of the same species be injected into the veins of the one to all appearance dead, we see with amazement this inanimate body return to life, gaining accessions of vitality with each new quantity of blood that is introduced, eventual beginning to breathe freely, moving with ease, and finally walking as it was wont to do, and recovering completely.” More or less distinct traces of the recognition of blood as the vehicle of life are found in Greek and Roman writers. The knowledge of the ancients on the subject may indeed have been based on the mere observation that an animal loses its life when it loses its blood: but it may deepen our sense of the wisdom and significance of the Law of Moses to know that the fact which it sets forth so distinctly and consistently, and in such pregnant connection, is so clearly recognized by modern scientific research.
Rather, For the soul of all flesh is its blood with its soul (i. e. its blood and soul together): therefore spake I to the children of Israel, Ye shall not eat the blood of any flesh, for the soul of all flesh is its blood, etc.