Before the Giving of the Torah they depended on constellations
We are told that before the Torah was given, even children, life and sustenance were dependent on constellations, but afterward God removed Yisrael from the influence of the stars and constellations. If a person does not keep the commandments, however, the stars and constellations will still hold sway over him. Finally we hear again that people grow old and die, and then return again as children.
On the wings of Abraham and by the thrust of the letter Hei engraved into the parchment of Torah, we are now propelled above the plane of planetary influence. We become shepherds of the stars, pilots of the planets, reacquiring control over our fate. Our future is hereby transformed to one of an immediate and complete redemption, in a process that embodies the mercy and tenderness of this great Book of Splendor. Illnesses, conferred to us by the stars, flare out of existence, like falling stars in the distant heavens.
The Zohar's words "For PEOPLE die when old and return to this world as children" have the effect of arresting the aging process. The letters kindle Light that regenerates our cells and our souls, infusing us with rejuvenescence so that we become youthful again, like children - for this is the ultimate destiny of human beings.