Giving And Withholding

Nolite sanctum dare canibus, et margaritas vestras nolite mittere ante porcos. Ac si dicat, Mandavi vobis diligere inimicos vestros, et non judicare eos, ut vos exhibeam misericordes ad illos, ut benefaciatis eis de corporalibus vestris, non de meis spiritualibus bonis, quoniam in natura vobis communes sunt, et non in fide. Mandavi autem vobis, ut non judicetis eos, qui in vobis peccaverint. Id vero non ideo praecepi, ut mysteriorum meorum secreta non pandatis eis, qui nolentes me scire, blasphemant, et spernunt. Videte Patrem vestrum Deum, ad cujus exemplum volui vos esse misericordes: carnalia beneficia dignis, et non dignis similiter praestat, numquid gratias spirituales? Nec enim dixi vobis de illo, qui Spiritum sanctum jubet descendere super gratos et ingratos, et dat benedictiones suas super justos et injustos: propter quod in vestris quidem estote simplices et benigni, in meis autem prudentes et cauti. Si tu vestiarium tuum studiosum, et clavicularium cellarii tui fidelem tibi requiris: quanto magis Deus talem requirit dispensatorem gratiarum suarum, qui bene tractando gratias ejus, faciat gratiores, non, male dispensando, reddat ingratas? Sicut enim si canibus dederis sanctum, aut porcis margaritas, nec sanctum canes sanctificat, nec margaritae nutriunt porcos, sed e contra canes coinquinant sanctum, et porci margaritas sordidant, vel confringunt: ita si hominibus caninos vel porcinos mores habentibus sanctum dederis, aut mysteria secreta credideris, nec sanctum illos sanctificat, nec mysteria veritatis eos illuminant, sed e contra ipsi sanctum coinquinant, et mysteria veritatis blasphemant. Opus Imperfectum in Matthaeum, Homilia XVII Source: Migne PG 56.727-8

Do not give what is holy to dogs, and do not cast your pearls before swine. 1 As if He says, 'I commanded you to love your enemies and not to judge them so that I might exhibit you as merciful to them, so that you may be of help to them in bodily matters, but not in my spiritual goods, because you have a common nature but not a common faith. And I commanded you not to judge those who have sinned against you, but I did not instruct you to reveal to them the secrets of my mysteries, for those who do not wish to know me will blaspheme and spurn them. Look to God the Father, for by His example I wish to make you merciful. May it not be that at the same time men are worthy of bodily benefits but not of spiritual graces? I did not say to you that He commands the Holy Spirit to descend upon the grateful and the ungrateful, and that He gives His blessing over the just and unjust. Because of which you should be simple and kind among yourselves, but in me prudent and cautious. If you are jealous of your wardrobe and you require trust for the key of your cellar, how much more does God require it for the dispensing of His graces, He who in the giving out His grace well makes grateful, and who does not dispense it poorly and give it to the ungrateful? So if you were to give something holy to a dog, or pearls to pigs, that which is holy would not sanctify the dogs, nor would pearls nourish pigs, but on the contrary the dogs would defile what is holy and the pigs would soil the pearls, or crush them. Thus if you give what is holy to men who have the ways of dogs and pigs, or you entrust the sacred mysteries to them, that which is holy will not sanctify them, nor will the mysteries of the truth enlighten them, but rather they will defile what is holy and blaspheme the mysteries of the truth. Opus Imperfectum on Matthew, from Homily 17 1 Mt 7.6