The practice of the Buddha's teaching is most commonly depicted by the image of a journey, the eight factors of the Noble Eightfold Path constituting the royal roadway along which the disciple must travel. The Buddhist scriptures, however, illustrate the quest for liberation in a variety of other ways, each of which throws a different spotlight on the nature of the practice. Although the alternative formulations inevitably draw upon the same basic set of mental factors as those that enter into the eightfold path, they structure these factors around a different "root metaphor" — an image which evokes its own particular range of associations and highlights different aspects of the endeavor to reach the cessation of suffering.
One of the groups of factors given special prominence in the Suttas included by the Buddha among the thirty-seven requisites of enlightenment is the five spiritual faculties: the faculties of faith, energy, mindfulness, concentration and wisdom. The term indriya, faculties, applied to this group as a whole is derived from the name of the ancient Vedic god Indra, ruler of the devas, and the term accordingly suggests the divine-like quality of control and domination. The five faculties are so designated because they exercise control in their own specific compartments of the spiritual life. As the god Indra vanquished the demons and attained supremacy among the gods, so each of the five faculties is called upon to subdue a particular mental disability and to marshal the corresponding potency of mind toward the breakthrough to final enlightenment.
The notion of faculty is partly akin to the ancient Greek conception of the virtues. Like the virtues, the faculties are active powers which coordinate and canalize our natural energies, directing them toward the achievement of an inward harmony and balance essential to our true happiness and peace. Since the faculties are to serve as agents of inward control, this implies that apart from their restraining influence our nature is not under our own control. Left to itself without the guidance of a superior source of instruction, the mind is a prey to forces that swell up from within itself, dark forces which hold us in subjection and prevent us from attaining our own highest welfare and genuine good. These forces are the defilements (kilesa). As long as we live and act under their dominion we are not our own masters but passive pawns, driven by our blind desires into courses of conduct that promise fulfillment but in the end lead only to misery and bondage. True freedom necessarily involves the attainment of inner autonomy, the strength to withstand the pushes and pulls of our appetites, and this is accomplished precisely by the development of the five spiritual faculties.
The qualities that exercise the function of faculties are of humble origin, appearing initially in mundane roles in the course of our everyday lives. In these humble guises they manifest as trustful confidence in higher values, as vigorous effort toward the good, as attentive awareness, as focused concentration, and as intelligent understanding. The Buddha's teaching does not implant these dispositions into the mind from scratch but harnesses those pre-existent capacities of our nature toward a supramundane goal — toward the realization of the Unconditioned — thereby conferring upon them a transcendental significance. By assigning them a task that reveals their immense potential, and by guiding them along a track that can bring that potential to fulfillment, the Dhamma transforms these commonplace mental factors into spiritual faculties, mighty instruments in the quest for liberation that can fathom the profoundest laws of existence and unlock the doors to the Deathless.
In the practice of the Dhamma each of these faculties has simultaneously to perform its own specific function and to harmonize with the other faculties to establish the balance needed for clear comprehension. The five come to fullest maturity in the contemplative development of insight, the direct road to awakening. In this process the faculty of faith provides the element of inspiration and aspiration which steers the mind away from the quagmire of doubt and settles it with serene trust in the Triple Gem as the supreme basis of deliverance. The faculty of energy kindles the fire of sustained endeavor that burns up obstructions and brings to maturity the factors that ripen in awakening. The faculty of mindfulness contributes clear awareness, the antidote to carelessness and the prerequisite of penetration. The faculty of concentration holds the beam of attention steadily focused on the rise and fall of bodily and mental events, calm and composed. And the faculty of wisdom, which the Buddha calls the crowning virtue among all the requisites of enlightenment, drives away the darkness of ignorance and lights up the true characteristics of phenomena.
Just as much as the five faculties, considered individually, each perform their own unique tasks in their respective domains, as a group they accomplish the collective task of establishing inner balance and harmony. To achieve this balanced striving the faculties are divided into two pairs in each of which each member must counter the undesirable tendency inherent in the other, thus enabling it to actualize its fullest potential. The faculties of faith and wisdom form one pair, aimed at balancing the capacities for devotion and comprehension; the faculties of energy and concentration form a second pair aimed at balancing the capacities for active exertion and calm recollection. Above the complementary pairs stands the faculty of mindfulness, which protects the mind from extremes and ensures that the members of each pair hold one another in a mutually restraining, mutually enriching tension.
Born of humble origins in everyday functions of the mind, through the Dhamma the five faculties acquire a transcendent destiny. When they are developed and regularly cultivated, says the Master, "they lead to the Deathless, are bound for the Deathless, culminate in the Deathless."