16.  But granted that a man is free from vice, and has reached the greatest heights of virtue:  I do not see what knowledge or power would justify him in venturing upon this office.  For the guiding of man, the most variable and manifold of creatures, seems to me in very deed to be the art of arts The art of arts.  This is the original of the frequently quoted commonplace, which in S. Gregory the Great’s Pastoral Care, i. 1, takes the form “ars artium est regimen animarum.” and science of sciences.  Any one may recognize this, by comparing the work of the physician of souls with the treatment of the body; and noticing that, laborious as the latter is, ours is more laborious, and of more consequence, from the nature of its subject matter, the power of its science, and the object of its exercise.  The one labours about bodies, and perishable failing matter, which absolutely must be dissolved and undergo its fate, Gen. iii. 19. even if upon this occasion by the aid of art it can surmount the disturbance within itself, being dissolved by disease or time in submission to the law of nature, since it cannot rise above its own limitations.