Key quote: Man “is hindered by the weakness of his reason, which is easily drawn into error by which he is cut off from the right way of reaching his end.”
1 Since it is plain from earlier chapters that divine providence controls rational creatures in a different way from other things, because they differ from other things in the way that their own nature was established, it remains to be shown that, by virtue of the dignity of their end, a higher mode of governance is used by divine providence in their case.
2 Now, it is obvious that, according to what befits their nature, they achieve a higher participation in the end. In fact, since they have an intellectual nature, they are able by its operation to attain to intelligible truth, and this is not possible for other things that are devoid of understanding. And, of course, because they can reach intelligible truth by their natural operation, it is clear that divine provision is made for them in a different way than for other things.
Inasmuch as man is given understanding and reason, by which he can both discern and investigate the truth; as he is also given sensory powers, both internal and external, whereby he is helped to seek the truth; as he is also given the use of speech, by the functioning of which he is enabled to convey to another person the truth that he conceives in his mind—thus constituted, men may help themselves in the process of knowing the truth, just as they may in regard to the other needs of life for man is “a naturally social animal.”
3 But, beyond this, man’s ultimate end is fixed in a certain knowledge of truth which surpasses his natural capacity: that is, he may see the very First Truth in Itself, as we showed above. Now, this is not granted to lower creatures, that is, the possibility of their reaching an end which exceeds their natural capacity. So, the different mode of governance in regard to men and in regard to other, lower creatures must be noted as a result of this end. For, the things that are related to an end must be proportionate to that end. So, if man is ordered to an end which exceeds his natural capacity, some help must be divinely provided for him, in a supernatural way, by which he may tend toward his end.
Notes In other words, we are higher than animals, not mere animals differently equipped.
4 Again, a thing of an inferior nature cannot be brought to what is proper to a higher nature except by the power of that higher nature. For example, the moon, which does not shine by its own light, becomes luminous by the power and action of the sun, and water, which is not hot of itself, becomes hot by the power and action of fire. Now, to see the very First Truth in Itself so transcends the capacity of human nature that it is proper to God alone, as we showed above. Therefore, man needs divine help so that he may reach this end.
Notes The only way to glimpse infinity, or truths not deducible from other known truths, is by divine assistance.
5 Besides, each thing attains its ultimate end by its own operation. Now, operation gets its power from the operating principle; thus, by the action of the semen there is generated a being in a definite species, whose power preexists in the semen. Therefore, man is not able by his own operation to reach his ultimate end, which transcends the capacity of his natural powers, unless his operation acquires from divine power the efficacy to reach the aforesaid end.
6 Moreover, no instrument can achieve its ultimate perfection by the power of its own form, but only by the power of the principal agent, although by its own power it can provide a certain disposition to the ultimate perfection. Indeed, the cutting of the lumber results from the saw according to the essential character of its own form, but the form of the bench comes from the skilled mind which uses the tool. Likewise, the breaking down and consumption of food in the animal body is due to the heat of fire, but the generation of flesh, and controlled growth and similar actions, stem from the vegetative soul which uses the heat of fire as an instrument.
Now, all intellects and wills are subordinated as instruments under a principal agent to God, Who is the first intellect and will. So, their operations must have no efficacy in regard to the ultimate perfection which is the attainment of final happiness, except through the divine power. Therefore, a rational nature needs divine help to obtain the ultimate end.
7 Furthermore, there are many impediments presented to man in the attaining of his end. For he is hindered by the weakness of his reason, which is easily drawn into error by which he is cut off from the right way of reaching his end. He is also hindered by the passions of his sensory nature, and by the feelings whereby he is attracted to sensible and lower things; and the more he attaches himself to these, the farther he is removed from his ultimate end, for these things are below man, whereas man’s end is above him.
He is further hindered by frequent bodily illness from the carrying out of his virtuous activities whereby he may tend toward happiness. Therefore, man needs divine help, but he may fall completely short of the ultimate end as a result of these obstacles.
8 Hence, it is said, in John (6:44): “No man can come to Me, except the Father, Who hath sent Me, draw him,” and again: “As the branch cannot bear fruit of itself, unless it abide in the vine, so neither can you, unless you abide in Me” (John 15:4).
9 By this we set aside the error of the Pelagians, who said that man could merit the glory of God by his free choice alone.