Katharsis

Katharsis (κάθαρσις) means purification or cleansing, from the verb kathairō, 'to make clean', and the adjective katharos, 'pure'. The word had a home in three domains at once: in religion, the ritual purity required to approach the sacred; in medicine, the purging of the body of harmful humors; and, drawing on both, in philosophy, the cleansing of the soul.

The notion of the soul's purification entered the tradition through the Pythagoreans and the mystery religions, for whom philosophy, music, and a disciplined way of life served to purify the soul and free it from the cycle of rebirth. Plato took this up in the Phaedo, where Socrates describes philosophy itself as a purification — the separation of the soul, as far as possible, from the distractions and deceptions of the body, so that it may attain the Forms with the mind alone. This is one with the philosopher's lifelong 'practice of death'.

Grades of virtue

The Neoplatonists built katharsis into a formal stage of the soul's ascent. Porphyry and others distinguished grades of virtue, ranking the 'purificatory' virtues — which cleanse the soul of the passions and turn it away from the body — above the merely civic virtues, as the necessary preparation for the higher, contemplative virtues that lift the soul toward the divine. (Aristotle, in a different key, gave the word a famous use in his Poetics, where tragedy effects a katharsis of pity and fear.)