Reply Obj. 4: The tree of life is a material tree, and so called because its fruit was endowed with a life-preserving power as above stated (Q. 97, A. 4). Yet it had a spiritual signification; as the rock in the desert was of a material nature, and yet signified Christ. In like manner the tree of the knowledge of good and evil was a material tree, so called in view of future events; because, after eating of it, man was to learn, by experience of the consequent punishment, the difference between the good of obedience and the evil of rebellion. It may also be said to signify spiritually the free-will as some say.
Reply Obj. 5: According to Augustine (Gen. ad lit. v, 5, viii, 3), the plants were not actually produced on the third day, but in their seminal virtues; whereas, after the work of the six days, the plants, both of paradise and others, were actually produced. According to other holy writers, we ought to say that all the plants were actually produced on the third day, including the trees of paradise; and what is said of the trees of paradise being planted after the work of the six days is to be understood, they say, by way of recapitulation. Whence our text reads: "The Lord God had planted a paradise of pleasure from the beginning" (Gen. 2:8). _______________________
SECOND ARTICLE [I, Q. 102, Art. 2]
Whether Paradise Was a Place Adapted to Be the Abode of Man?
Objection 1: It would seem that paradise was not a place adapted to be the abode of man. For man and angels are similarly ordered to beatitude. But the angels from the very beginning of their existence were made to dwell in the abode of the blessed—that is, the empyrean heaven. Therefore the place of man's habitation should have been there also.
Obj. 2: Further, if some definite place were required for man's abode, this would be required on the part either of the soul or of the body. If on the part of the soul, the place would be in heaven, which is adapted to the nature of the soul; since the desire of heaven is implanted in all. On the part of the body, there was no need for any other place than the one provided for other animals. Therefore paradise was not at all adapted to be the abode of man.
Obj. 3: Further, a place which contains nothing is useless. But after sin, paradise was not occupied by man. Therefore if it were adapted as a dwelling-place for man, it seems that God made paradise to no purpose.
Obj. 4: Further, since man is of an even temperament, a fitting place for him should be of even temperature. But paradise was not of an even temperature; for it is said to have been on the equator—a situation of extreme heat, since twice in the year the sun passes vertically over the heads of its inhabitants. Therefore paradise was not a fit dwelling-place for man.
On the contrary, Damascene says (De Fide Orth. ii, 11): "Paradise was a divinely ordered region, and worthy of him who was made to God's image."
I answer that, As above stated (Q. 97, A. 1), Man was incorruptible and immortal, not because his body had a disposition to incorruptibility, but because in his soul there was a power preserving the body from corruption. Now the human body may be corrupted from within or from without. From within, the body is corrupted by the consumption of the humors, and by old age, as above explained (Q. 97, A. 4), and man was able to ward off such corruption by food. Among those things which corrupt the body from without, the chief seems to be an atmosphere of unequal temperature; and to such corruption a remedy is found in an atmosphere of equable nature. In paradise both conditions were found; because, as Damascene says (De Fide Orth. ii, 11): "Paradise was permeated with the all pervading brightness of a temperate, pure, and exquisite atmosphere, and decked with ever-flowering plants." Whence it is clear that paradise was most fit to be a dwelling-place for man, and in keeping with his original state of immortality.