St. Augustine insists upon finding the internal and invisible cause of sin since it is always a consequence of reason and free will. Man turns from God and looks at himself, imagines independence from his Maker, and chooses to tempt fate in eating the forbidden fruit. Much later in Scripture Christ Jesus reminds us that those things which proceed out of the mouth come forth from the heart; and they defile the man. (St. Matthew xv. 18) Evil emerges then from the soul or spirit that is within a man. Thus, with our primal progenitors an internal and invisible sin preceded and caused its outward manifestation. By the time that Adam and Eve had eaten the forbidden fruit, they were already moved and defined by sin. Their freedom of choice is not thwarted by God. He knows that in the moment that they eat of the fruit they shall surely die.
So what was that original, spiritual sin that overtook and redefined man in the Garden of Eden? Proverbs teaches us that before destruction the heart of man is haughty. (Prov. xviii. 12) St. Augustine teaches us that the fall that happens in secret inevitably precedes the fall that occurs in broad daylight. (DCD xiv. 13) And most commentators agree that this was the sin of pride. Pride here is synonymous with hubris or arrogance. It is negative and destructive, and denotes that swelling or inflation of self-importance that longs to lord it over everyone and everything. St. Thomas Aquinas tells us that it is an inordinate desire to excel or surpass. (S.T. i. ii. 84. 2) Pride is thus unmeasured and immoderate passion for the attainment of the self’s good. It is self-love that is no longer measured and moved by love of the Good. As the self swells, the pursuit of the Good is converted into the passion for my good. Man forfeits his subjection to God and raises himself above that which is appointed to him according to the Divine rule or measure, against the saying of the Apostle “But we will not glory beyond our measure; but according to the measure of the rule which God hath measured to us.” (2 Cor. x. 13) Wherefore it is written (Sirach x. 14): “The beginning of the pride of man is to fall off from God” because, to wit, the root of pride is found to consist in man not being, in some way, subject to God and His rule. (ST ii. ii. 162. 5) Pride is contempt for and aversion to the Divine governance of man’s nature. Through it man decides to become the molder and fashioner of his own good or end, refusing to acquiesce in God’s will for his nature.
So man becomes a sophist. A sophist is one for whom truth is relative –i.e. truth is what is useful for and productive of happiness for the individual. The end is individual happiness or contentment; the means is whatever thought, word, or work ensures its acquisition. The happiness of this character-state depends wholly upon treating everyone and every thing as useful tools in the acquisition of selfish ends. Pride engenders the delusional belief that the self can exist apart from all and subject to none. It convinces a man that he is free, independent, and unaccountable. In its most extreme form, it excludes friendship with both God and man.
As it is pictured in Genesis, it does, however, reveal its own weakness. Eve might have thought that she could eat of the forbidden fruit without harm and in isolation from God and even her husband. But something within moved her to share it with Adam. Maybe that something was the inherent and natural truth that man cannot help but relate to and depend upon others. Perhaps pride, after all, is not as strong and self-reliant as it thinks itself to be. Perhaps even this primal and mortal sin reveals man’s need for the other, and thus for a principle beyond his own fragile nature. As perverse as this may sound, even the blame-game that follows the discovery of sin reveals a need for others to bear its burden and censure. Pride is at first concealed. But with the forfeiture of Divine co-inherence, human nature is so psychologically fragile and weak that it needs a false god in the other to justify and excuse its choice.