In "The Truth Shall Make You Free"(1943), the phrase "life force" first appears.
page 73,
Notice here the same expression "living soul" as in connection with the lower animals when created. In the Hebrew text the expression is _nephesh chayyah_. (Genesis 1:20,21,24,30) God made the human creature, man, or Adam, to be a "living soul" by first creating the human body then breathing into it, not a soul, but the "breath of life", the energizing power, and then combining that life force with the body. A "living soul" means a living creature; and on earth it means a creature that breathes while alive. Man, or Adam, was a living soul like the lower animals, having a material body and breathing the atmosphere of the firmament the same as did those animals; only man, or Adam, was of a higher order, having an upright form and being of far superior intelligence. He was also in God's likeness and image. The lower animal souls die. Can the human soul die? And if it can die, is it nevertheless possible for it under right conditions to live forever? The Bible gives answer.
page 76,
Because the blood circulating within the blood vessels is the basis of human and animal life, the life is said to be in the blood: "Flesh with the soul thereof, the blood therof, shall ye not eat; and surely your blood of your souls will I require." (Genesis 9:4,5, _Roth_., margin) "As for the soul of the flesh, in the blood it is, therefore have I given it unto you upon the altar, to put a propitiatory-covering over your souls; for the blood it is which by virture of the soul maketh propitiation." (Leviticus 17:11, _Roth_., margin) Therefore the life, or _soul_ can not survive and exist as an intelligent creature apart from the body. Like the blood drained from the body, so life or soul does not exist apart from the body. When the life forces are withdrawn from the body, the _soul_ or living creature dies, and not merely the body.
pages 108/109,>/p>
No promise had been made to Adam of life at last in heaven, even if he should remain obedient and faithful. Truly, the spirit of the one dying returns to God who gave it. What was it that God gave Adam, comgining it with his earthly body? Read again the record, at Genesis 2:7: "God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a lving soul." God gave man the breath of life, that is, the life forces or the power of life which is sustained by brathing. This is what is meant by "the spirit", and this is what returns to God who gave it. Regarding the spirit that returns, the same book of Ecclesiastes, at 3:19-21, states: "Therefore the death of man, and of beasts is one, and the condition of them both is equal: as man dieth, so they also die: all things breathe alike, and man hath nothing more than beast: all things are subject to vanity, And all things go to one place: of earth they were made, and into earth they return together. Who knoweth if the spirit of the children of Adam ascend upward, and if the spirit of the beasts descend downware?: (_Douay_) By reason of the workding oft he Douay translation it is not discernible that the above words _breathe_ and _spirit_ translate the same Hebrew word, _ruach_; which word is also translated _air_ and _wind_ in still other Bible verses. - Job 41:16;1:19; Genesis 8:1.