α) An analysis of this definition shows that (1) merit is found only in such works as are positively good; (2) merit and reward are correlative terms which postulate each other; (3) merit supposes two distinct persons, one who deserves and another who awards; (4) the relation between merit and reward is based on justice, not on benevolence or mercy. The last-mentioned determination is by far the most important of the four.(407) β) Ethics and theology clearly distinguish two kinds of merit: (1) condign merit,(408) which is merit in the strict sense (_meritum adaequatum sive de condigno_), and (2) congruous merit (_meritum inadaequatum sive de congruo_), so called because of the congruity, or fitness, that the claim should be recognized. Condign merit presupposes some proportion between the work done and the reward given in compensation for it (_aequalitas s. condignitas dati et accepti_). It is measured by commutative justice and thus confers a real claim to a reward. For example, a conscientious workman has a strict claim to his wage. Owing to the lack of intrinsic proportion between service and reward, congruous merit can claim a remuneration only on grounds of fairness. A distinction between these two kinds of merit was already made by the Fathers, though not in the terms of present-day theology. It was known to the older Scholastics and emphasized anew by Luther’s famous adversary Johann Eck.(409) No relation of strict justice is conceivable between the Creator and His creatures. On the part of God there can only be question of a gratuitous promise to reward certain good works,—which promise He is bound to keep because He is veracious and faithful.(410) b) Two other terms must also be clearly defined in order to arrive at a true conception of the gratuity of Christian grace. They are prayer for grace,(411) and a capacity or disposition to receive it.(412) To pray means to incite God’s liberality or mercy by humble supplication. α) Despite the contrary teaching of Vasquez(413) and a few other theologians, congruous merit and prayer are really distinct because one can exist without the other. As the angels in Heaven are able to pray for us without earning a _meritum de congruo_, so conversely, all salutary works are meritorious even without prayer. Moreover, humble supplication does not involve any positive service entitled to a reward. There is another important and obvious distinction, _viz._: between purely natural prayer (_preces naturae_) and supernatural prayer inspired by grace (_oratio supernaturalis_). β) Capacity or disposition, especially when it takes the form of preparation, may be either positive or negative. Positive capacity is defined as “that real mode by which a subject, in itself indifferent, becomes apt to receive a new form.” Such a capacity or disposition always entails a claim to its respective form.