The virtues, though they beget each other, yet have their origin in the three powers of the soul–all except those virtues that are divine. For the ground and principle of the four cardinal virtues, both natural and divine–sound understanding, courage, self-restraint and justice, the progenitors of all the other virtues–is the divine Wisdom that inspires those who have attained a state of mystical prayer. This Wisdom operates in a fourfold manner in the intellect. It activates not all the four virtues simultaneously, but each one individually, as is appropriate and as it determines.
It activates sound understanding in the form of light, courage as clear-sighted power and ever-moving inspiration, self-restraint as a power of sanctification and purification, and justice as the dew of purity, joy-inducing and cooling the arid heat of the passions. In every one who has attained the state of perfection it activates each virtue fully, in the appropriate form.
~St Gregory of Sinai
Prayerful Life 