"by consent, . . . by silence, by not preventing, by not denouncing."

"a person is bound to restitution not only on account of someone else's property which he has taken, but also on account of the injurious taking. Hence whoever is cause of an unjust taking is bound to restitution. This happens in two ways, directly and indirectly. Directly, when a man induces another to take, and this in three ways. First, on the part of the taking, by moving a man to take, either by express command, counsel, or consent, or by praising a man for his courage in thieving. Secondly, on the part of the taker, by giving him shelter or any other kind of assistance. Thirdly, on the part of the thing taken, by taking part in the theft or robbery, as a fellow evil-doer. Indirectly, when a man does not prevent another from evil-doing (provided he be able and bound to prevent him), either by omitting the command or counsel which would hinder him from thieving or robbing, or by omitting to do what would have hindered him, or by sheltering him after the deed. All these are expressed as follows:

By command, by counsel, by consent, by flattery, by receiving, by participation, by silence, by not preventing, by not denouncing [(iussio, consilium, consensus, palpo, recursus, participans, mutus, non obstans, non manifestans)].

     "It must be observed, however, that in five of these cases the cooperator is always bound to restitution. First, in the case of command: because he that commands is the chief mover, wherefore he is bound to restitution principally. Secondly, in the case of consent; namely of one without whose consent the robbery cannot take place. Thirdly, in the case of receiving; when, to wit, a man is a receiver of thieves, and gives them assistance. Fourthly, in the case of participation; when a man takes part in the theft and in the booty. Fifthly, he who does not prevent the theft, whereas he is bound to do so; for instance, persons in authority who are bound to safeguard justice on earth, are bound to restitution, if by their neglect thieves prosper, because their salary is given to them in payment of their preserving justice here below.
     "In the other cases mentioned above, a man is not always bound to restitution: because counsel and flattery are not always the efficacious cause of robbery. Hence the counsellor or flatterer is bound to restitution, only when it may be judged with probability that the unjust taking resulted from such causes."

     Thomas Aquinas, Summa theologiae II-II.62.7.Resp., trans. FEDP (Shapcote).  Latin from Corpus Thomisticum.  Also Super Sent., lib. 4 d. 15 q. 1 a. 5 qc. 3 co.
     I was put onto this by Kevin L. Flannery (First things no. 254 (June/July 2015):  55 (54-55), who, however, may (?) conflate "the failings of pastors and professors" with the failings of those truly "bound" to confront or prevent, e.g. "persons in authority who are bound to safeguard justice on earth".
     Flannery says that the origin of the quotation has not been identified.  Can I track it down?