"But it is lawful for a husband to demand the marriage debt from his wife, even if she is unwilling, because she owes it to him by virtue of the marriage contract."

"It is much graver to corrupt the faith, whereby the soul lives, than to forge money, which supports temporal life."

"Good can exist without evil, whereas evil cannot exist without good."

"The end justifies the means, when the end is good and the means are not evil in themselves."

"The truth of our faith becomes a matter of ridicule among the infidels if any Catholic, not gifted with the necessary scientific learning, presents as dogma what scientific scrutiny shows to be false."