Since the descent of the soul is referred to as a Fall from Grace, or from Paradise, we find astronomical metaphors being widely used to symbolize that. We have already mentioned the notion of the Shekinah as a stone that fell from heaven to the earth, and in Revelation 6:13 we see, "And the stars of heaven fell unto the earth". In Ezekiel 1:14 we read, "The living creatures ran and returned as the appearance of a flash of lightning". The Tree is quite often depicted with a lightning bolt connecting the spheres in the order of their descent (ie. 1,2 3 etc).
Egyptians used the daily path of the sun as a metaphor for the soul's journey. The noontime sun represented the soul in it's rigthful home in the heaven's, the setting sun symbolized the incarnation into a body, the nighttime sun figured the soul's journey through the darkness that is life in a body, and the sunrise was it's release (the second death). Note that this is the reason that Moslems and Jews begin their day at sundown. This is also the source of the term "journey to the east".
The yearly path of the sun was used, as well, to illustrated the same journey, with Easter being analogous to the sunrise; hence the sunrise Easter services.
If we were to take at face value what we read surrounding ancient beliefs about the path taken by the soul, we would come away with the conclusion that, "It was a postulate of ancient philosophers, that the passage of the soul from heaven to earth was effected through the Zodiac and seven planets"; through the 7 planetary spheres, represented by Jacobs ladder, the souls emanating from the Deity descended to be united to their human bodies; and through those seven spheres they must reascend, to return to their origin and home.
But since we know that these philosophers sought to conceal their vital doctrines from the ignorant and vulgar, we can presume that these stories are merely the form of their philosophy which was given to the outside world; the exoteric and not the esoteric version, in other words. Undoubtably the story of the soul's sojourn through the planetary spheres was used as an astronomical and astrological teaching aid, and like the Kaballah, was not to be understood as a natural history. Instead of using language like "ancient philosphers believed" we will say that "they taught", this or that.
Ancient Philosophers, like Plato, taught that the soul of man had it's origins in the heavens, that is the Milky Way, where is said to have dwelt among the stars until it descends to be imprisoned in matter. It first surrounds itself with a body composed of the substance of the stars, and descends thru the several spheres. What we here call "life", is to the soul, a death of sorts (the first death- hence the name "Book of the Dead" from Egypt). While in the body the soul looks toward it's source and strives to return from where it came.
Cicero writes (in "Vision of Scipio") that a soul has been supplied to men from those eternal flames which we call constellations and stars, and those who having been released from their bodies inhabit that place which we behold in the sky. The souls descend to earth from the stars or constellations and after death ascend to the Milky Way. That is, we come from and return to the stars.
Remember that this is an allegory, I believe that the real meaning of these statements is that we are all made or star dust, in other words, the same substance as the rest of the Universe; and early expression of Atomism. It is also a restatement of the Hermetic slogan, "As above, so below".
The planets then, were seen as "the mediating powers by which the emanation of God, or the germ of life descended from heaven and became incarnate on earth". Plato speaks of demons or spirits, who are "intermediate between the divine and the mortal", mediators between gods and men, who convey the souls of men down to earth and thence to heaven; a task that we now attribute to Mercury alone. [Note that there is a magical side to the Kaballah that deals with commmunicating with these spirits.]
The order of the spheres shows the earth and the heavens at the extremes, the descent of the souls is from the Zodiac, to Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon. The souls are said to come thru the Gate of Cancer and leave thru the Gate of Capricorn (sounds like tropics), originally called the Gates of the Sun. Note the Moon rules Cancer and Saturn rules Capricorn.
Those who have read Dante's "Divine Comedy" will recognize that this is the scheme that he uses in his trilogy. This illustration is taken from Volume 3, "Paradise", and shows the spheres as concentric circles.
This description from Canto 2 of that volume, will be easily recognizable to any one familiar with modern descriptions of the tree of life:
"Within the highest Heaven of God's Peace revolves a body in whose power lies the essence of all things contained therein. The next sphere which is lit with myriad eyes divides this essence into many types, distinct from it and yet contained in it. The other spheres, by various differences direct their own distinctive qualities to their own ends and frituful operations. These universal organs proceed from grade to grade, receiving power from above, acting on those below."
Later in Canto 21, he offers a description that reminds us of the story of Jacob from Genesis:
I saw- color of gold as it reflects the sun- a ladder gleaming in the sky, stretching beyond the reach of my sight. And I saw coming down the golden rungs so many splendors that I thought the heavens were pouring out the light of every star.
In the image of the astronomer above, we can see on the back of his chair, the stars and Zodiac at the top, then in pre-Ptolemeic descending order, Saturn, Jupiter, Mars, the Sun, Venus, and Mercury. He holds the earth in his hand, and the full moon is in the sky.