And though it be their sin and vanity that is the cause [of lust], it is nevertheless your sin to be the unnecessary occasion…You must not lay a stumbling-block in their way, nor blow up the fire of their lust…You must walk among sinful persons as you would do with a candle among straw or gunpowder; or else you may see the flame which you did not foresee, when it is too late to quench it.
