14 I blush to speak of it, it is so shocking; yet though sad, it is true. How comes this plague of the agapetæ to be in the church? Whence come these unwedded wives, these novel concubines, these harlots, so I will call them, though they cling to a single partner? One house holds them and one chamber. They often occupy the same bed, and yet they call us suspicious if we fancy anything amiss. A brother leaves his virgin sister; a virgin, slighting her unmarried brother, seeks a brother in a stranger. Both alike profess to have but one object, to find spiritual consolation from those not of their kin; but their real aim is to indulge in sexual intercourse. It is on such that Solomon in the book of proverbs heaps his scorn. “Can a man take fire in his bosom,” he says, “and his clothes not be burned? Can one go upon hot coals and his feet not be burned?”
Source: Letters (New Advent)