Cardinal Wiseman.

"Do you construe that passage in Leviticus (xviii. 18) as prohibiting marriage with a deceased wife's sister, or merely as saying that a man should not take two wives together, at the same time, being so related?" "Certainly, that verse appears to have the latter meaning, that two sisters should not be living together in the same house, as wives of the same person." .... "Is such a marriage held by your Church as prohibited in Scripture?" Certainly not. It is considered a matter of ecclesiastical legislation."