α) With regard to the first-mentioned point it will be well, for the sake of clearness, to adopt Palmieri’s distinction between physical and moral capacity.(167) Man sins whenever he transgresses the law or yields to temptation. This would be impossible if he were physically unable to keep the whole law and resist temptation. Hence he must be physically able to do that which he is obliged to do under pain of sin, though in this or that individual instance the difficulties may be insuperable without the aid of grace. To put it somewhat differently: Baius and Jansenius hold that fallen man can perform no morally good works because of physical or moral impotence on the part of the will. This assumption is false. Man is physically able to perform good works because they are enjoined by the moral law of nature under pain of sin; he is morally able because, in spite of numerous evil tendencies, not a few gentiles and unbelievers have led upright lives and thereby proved that man can perform good works without the aid of grace.(168) This is also the teaching of St. Thomas.(169) β) It is an expressly defined dogma that the process of justification starts with theological faith (_fides_), preceded by the so-called grace of vocation, which prepares and effects conversion. To say, as Baius did, that all good works performed in a state of unbelief are so many sins, is tantamount to asserting that the preliminary acts leading up to faith, and which the unbeliever performs by the aid of prevenient grace, are sinful; in other words, that God requires the unbeliever to prepare himself for justification by committing sin. This is as absurd as it is heretical.(170) The whole argument of this section applies _a fortiori_ to the theory that no act can be morally good unless prompted by both theological charity and theological faith.(171) 2. We must now define the limitations of fallen nature unaided by grace. Though the graces dispensed by Providence even for naturally good deeds are in the present economy _de facto_ nearly all supernatural, nothing prevents us from conceiving a different economy, consisting of purely natural helps, such as would have been necessary in the state of pure nature.(172) As regards the limitations of man’s moral power in the natural order, we may say, in a general way, that the will is able to keep the easier precepts of the moral law of nature without the assistance of grace (either supernatural or natural). However, as it is impossible in many instances to determine just where the easier precepts end and the more difficult ones begin, a broad field is left open for theological speculation. a) Theologians are practically unanimous in holding that man cannot observe the natural law in its entirety for any considerable length of time without the aid of grace.