Let us consider how great a commodity of doctrine exists in books; how easily, how secretly, how safely they expose the nakedness of human ignorance without putting it to shame. These are the masters who instruct us without rods and ferules, without hard words and anger, without clothes or money. If you approach them, they are not asleep; if investigating you interrogate them, they conceal nothing; if you mistake them, they never grumble; if you are ignorant, they cannot laugh at you.