"natural" or "animal" love, which can never be sinful. A second kind of love, however, "mind-directed" love, can fail in one of three ways and so be sinful, and in explaining this Virgil also explains the way the central portion of Purgatorio is structured around the concept of the seven deadly sins. One can go wrong by loving things one should not, (pride, envy, and anger), by loving what one should love, but with insufficient intensity (sloth) or by loving as ends in themselves things that one should love only in proper relationship to primary ends. In indulging these impulses, therefore, and so committing sins, one is motivated by a species of love. In canto 18, however, Dante pursues the relationship between free will and love one step further. If love is a powerful force innate in each individual, "what merit is there in loving good or blame in loving ill?" The answer is that "Reason must surely guard the threshold of consent," for only with full consent of the will can a soul be held guilty of sin. Traditional medieval psychology held that sin involved three steps: attraction, delectation or delight, and consent. One perceives with the senses something to which one is attracted and then forms within the mind an image of the object of attraction in which to take delight. These two actions, the attraction or perception and the taking of delight, are both instinctive, and according to Virgil, are no more culpable than honey-making in a bee; they correspond to canto 17's animal or natural love which can never be sinful. However, while love arises of necessity in everyone, reason can check its potentially damning power. At this central point in the Comedy, we learn retrospectively, by a kind of "back illumination," to use a term of John Freccero's, the principles by which the souls in Inferno willed their own damnation: their Reason did not control the threshold of assent. Dante's geography in Purgatory is wholly his own invention, eve...
