Regarding partial indulgences, with the abolishment of the former determination of days and years, a new norm or measurement has been established which takes into consideration the action itself of the faithful Christian who performs a work to which an indulgence is attached.
Since by their acts the faithful can obtain, in addition to the merit which is the principal fruit of the act, a further remission of temporal punishment in proportion to the degree to which the charity of the one performing the act is greater, and in proportion to the degree to which the act itself is performed in a more perfect way, it has been considered fitting that this remission of temporal punishment which the Christian faithful acquire through an action should serve as the measurement for the remission of punishment which the ecclesiastical authority bountifully adds by way of partial indulgence.
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n. 5—The faithful who at least with a contrite heart perform an action to which a partial indulgence is attached obtain, in addition to the remission of temporal punishment acquired by the action itself, an equal remission of punishment through the intervention of the Church.