And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil (Gen. 2:9).
The majority of men judge the good to lie in that which gratifies the senses, and there is a certain identity of name between that which is, and that which appears to be “good.”
For this reason that desire which arises towards what is evil, as though towards good, is called by Scripture “the knowledge of good and evil,” with “knowledge,” as we have said, expressing a certain mixed disposition.
It speaks of the fruit of the forbidden tree not as a thing absolutely evil (because it is decked with good), nor as a thing purely good (because evil is latent in it), but as compounded of both, and declares that the tasting of it brings to death those who touch it.
It almost proclaims aloud the doctrine that the very actual good is in its nature simple and uniform, alien from all duplicity or conjunction with its opposite, while evil is many-coloured and fairly adorned, being esteemed to be one thing and revealed by experience as another, the knowledge of which (that is, its reception by experience) is the beginning and antecedent of death and destruction.
It was because he saw this that the serpent points out the evil fruit of sin, not showing the evil manifestly in its own nature (for man would not have been deceived by manifest evil), but giving to what the woman beheld the glamour of a certain beauty, and conjuring into its taste the spell of a sensual pleasure, he appeared to her to speak convincingly:
“And the woman saw that the tree was good for food, and that it was pleasant to the eyes to behold, and fair to see; and she took of the fruit thereof and did eat” (Gen. 3:5-6). And that eating became the mother of death to men.
This, then, is that fruit-bearing of mixed character, where the passage clearly expresses the sense in which the tree was called “capable of the knowledge of good and evil,” because, like the evil nature of poisons that are prepared with honey, it appears to be good in so far as it affects the senses with sweetness: but in so far as it destroys him who touches it, it is the worst of all evil.
Thus when the evil poison worked its effect against man’s life, then man, that noble thing and name, the image of God’s nature, was made, as the prophet says, “like unto vanity” (Ps. 143:4 [LXX]).
The image, therefore, properly belongs to the better part of our attributes; but all in our life that is painful and miserable is far removed from the likeness to the Divine.
Gregory of Nyssa (c 335 – after 394): On the Making of Man, 20 (slightly adapted).