When Jovinian attempted to revive the Stoic theory of the absolute equality of all virtues and vices, he met with strenuous opposition on the part of St. Jerome, who wrote a special treatise _Contra Iovinianum_, in which he said: “Each of us receives grace according to the measure of the grace of Christ (Eph. IV, 7); not as if the measure of Christ were unequal, but so much of His grace is infused into us as we are capable of receiving.”(1185) St. Augustine teaches that the just are as unequal as the sinners. “The saints are clad with justice (Job XXIX, 14), some more, some less; and no one on this earth lives without sin, some more, some less: but the best is he who has least.”(1186) But, we are told, life as such is not capable of being increased; how then can there be an increase of spiritual life? St. Thomas answers this objection as follows: “The natural life pertains to the substance of man, and therefore can be neither augmented nor diminished; but in the life of grace man participates _accidentaliter_, and consequently he can possess it in a larger or smaller degree.”(1187) c) From what we have said it is easy to understand the distinction which theologians make between justification as _gratia prima_ and justification as _gratia secunda_. The latter is merely another term for an increase of grace after justification. α) Such an increase may be effected either _ex opere operantis_, that is, by good works, or _ex opere operato_, through the sacraments, and is called justification (_iustificatio_, δικαίωσις) partly because Sacred Scripture refers to it by that name(1188) and partly because “to become just” (_iustum fieri_) and “to become more just” (_iustiorem fieri_) both imply true sanctification. In this connection the question may be raised whether sanctifying grace is diminished by venial sin. Venial sin does not destroy the state of grace and consequently cannot augment or diminish grace. To assume that it could, would lead to the absurd conclusion that a definite number of venial sins might eventually grow into a mortal sin, or that repeated venial sins gradually diminish grace until finally it disappears. The first-mentioned assumption is impossible because venial differs generically from mortal sin, and a transition from the one to the other would be a μετάβασις εἰς ἄλλο γένος. The second assumption would entail the heretical inference that the state of grace can be lost without mortal sin.(1189) No doubt venial sin influences the state of grace unfavorably; but this evil influence must be conceived as indirect—by committing venial sins man weakens his will-power, and temptation eventually grows so strong as to make mortal sin inevitable. “He that contemneth small things, shall fall little by little.”(1190) β) If we inquire how sanctifying grace increases in the soul, we find that the process must be conceived as a growing intensity analogous to that of light and heat in the physical order.