Appetites are like…

Darkness and coarseness will always be with a soul until its appetites are extinguished. The appetites are like a cataract on the eye or specks of dust in it; until removed they obstruct vision…The affections and appetites deprive them of a treasure of divine light. Any appetite, even one that is but slightly imperfect, stains and defiles the soul.
–Saint John of the Cross (1542-1591)