The light of holiness
Chosen souls are, in My hand, lights which I cast into the darkness of the world and with which I illumine it. As stars illumine the night, so chosen souls illumine the earth. And the more perfect a soul is, the stronger and the more far-reaching is the light shed by it. It can be hidden and unknown, even to those closest to it, and yet its holiness is reflected in souls even to the most distant extremities of the world (Diary, 1601).
Devotion to the souls in Purgatory contains in itself all the works of mercy, which supernaturalized by a spirit of faith, should merit us Heaven. de Sales