“Sanity, it would seem, was a dangerously contagious disease.”

“Against the disease of writing one must take special precautions, since it is a dangerous and contagious disease.”

“No company is preferable to bad. We are more apt to catch the vices of others than virtues, as disease is far more contagious than health.”

“It is a fair, even-handed, noble adjustment of things, that while there is infection in disease and sorrow, there is nothing in the world so irresistibly contagious as laughter and good humour.”

“Oh Senor" said the niece. "Your grace should send them to be burned (books), just like all the rest, because it's very likely that my dear uncle, having been cured of the chivalric disease, will read these and want to become a shepherd and wander through the woods and meadows singing and playing and, what would be even worse, become a poet, and that, they say, is an incurable and contagious disease.”

“I swear stupidity is contagious and as hard as I try, logic doesn't seem to be the cure.”