In theoretical and practical sciences, virtues whose boundaries have been defined are divided into two. The first is acquired through a person's learning and deliberate effort. In acquiring such virtues, there is a need for zamān (time), striving, and the attainment of malaka (habitual faculty). The strengthening of virtue in a person, even if with little effort according to the degree of intelligence or dullness in some people, occurs gradually and imperceptibly, like the slow development of the individual. Such was the case with Jesus, son of Mary, and John, son of Zechariah. (Mizān, 58)
Virtue is sometimes acquired through habit, depending on nature and temperament, and sometimes through learning. (Mizān, 59)
Even though virtues are many, all their branches and varieties can be gathered into four categories: ḥikma (wisdom), courage, chastity, and justice. Ḥikma is the virtue of the intellect; courage is the virtue of anger; chastity is the virtue of shahwa (desire); and justice consists in the proper combination of these faculties. All affairs are perfected through justice. For this reason, it has been said: "The heavens and the earth are established by justice." (Mizān, 64)
Knowledge is both an obligation (farīḍa) and a virtue. Knowledge that is an obligation is that which a person must know in order to fulfill the duties of their religion. Knowledge that is a virtue, on the other hand, is the Book and the Sunna...