DILIGENZA. – In its primary meaning, this term denotes assiduous and exquisite care, particular attention in doing something. In spiritual life and asceticism as well, it fundamentally retains the same meaning. Thus, a person is called diligent when he considers and weighs his duties and strives to fulfill them in the best possible manner. It is first and foremost a Christian virtue, as well as a natural endowment, which inspires admiration and respect. It is opposed to negligence, which denotes habitual carelessness in what one is obliged to do.
Diligence is defined by s. Tommaso as “a right choice of those means which lead to the end” (Summ. Theol., 2°-2°, q. 54, a. 3). It therefore forms part of the virtue of prudence, which is precisely the virtue that directs the intellect in every action to discern what helps or hinders the attainment of the end.
It can be distinguished from prudence insofar as diligence acts more upon the will than upon the intellect. The will, enlightened by prudence in the choice of means, strives, through the virtue of diligence, to put them into practice and to attain the end. Diligence frees the soul from seccidia and thoughtlessness; it therefore requires daily commitment and effort, especially in small matters that are usually neglected. But small things contribute to perfection, which is not a small thing: care in performing them well is therefore one of the means most recommended by spiritual teachers for acquiring this virtue. Other means indicated by the Fathers and the saints are, in addition to prayer to God (cf. the magnificent elevation on prudence in Sap. 9), the habit of fulfilling one’s duties with peace of mind, of attending to each one as though it were the only one imposed upon us, of not postponing until tomorrow what can be done today, of weighing the pros and cons of everything without haste, of drawing upon one’s own experience and that of others, and of seeking advice from sensible and learned persons.