Reply Obj. 4: A man is not bound to pay tithes on what he has lost by theft or robbery, before he recovers his property: unless he has incurred the loss through his own fault or neglect, because the Church ought not to be the loser on that account. If he sell wheat that has not been tithed, the Church can command the tithes due to her, both from the buyer who has a thing due to the Church, and from the seller, because so far as he is concerned he has defrauded the Church: yet if one pays, the other is not bound. Tithes are due on the fruits of the earth, in so far as these fruits are the gift of God. Wherefore tithes do not come under a tax, nor are they subject to workmen's wages. Hence it is not right to deduct one's taxes and the wages paid to workmen, before paying tithes: but tithes must be paid before anything else on one's entire produce. _______________________
THIRD ARTICLE [II-II, Q. 87, Art. 4]
Whether Tithes Should Be Paid to the Clergy?
Objection 1: It would seem that tithes should not be paid to the clergy. Tithes were paid to the Levites in the Old Testament, because they had no portion in the people's possessions, according to Num. 18:23, 24. But in the New Testament the clergy have possessions not only ecclesiastical, but sometimes also patrimonial: moreover they receive first-fruits, and oblations for the living and the dead. Therefore it is unnecessary to pay tithes to them.
Obj. 2: Further, it sometimes happens that a man dwells in one parish, and farms in another; or a shepherd may take his flock within the bounds of one parish during one part of the year, and within the bounds of another parish during the other part of the year; or he may have his sheepfold in one parish, and graze the sheep in another. Now in all these and similar cases it seems impossible to decide to which clergy the tithes ought to be paid. Therefore it would seem that no fixed tithe ought to be paid to the clergy.
Obj. 3: Further, it is the general custom in certain countries for the soldiers to hold the tithes from the Church in fee; and certain religious receive tithes. Therefore seemingly tithes are not due only to those of the clergy who have care of souls.
On the contrary, It is written (Num. 18:21): "I have given to the sons of Levi all the tithes of Israel for a possession, for the ministry wherewith they serve Me in the Tabernacle." Now the clergy are the successors of the sons of Levi in the New Testament. Therefore tithes are due to the clergy alone.
I answer that, Two things have to be considered with regard to tithes: namely, the right to receive tithes, and the things given in the name of tithes. The right to receive tithes is a spiritual thing, for it arises from the debt in virtue of which the ministers of the altar have a right to the expenses of their ministry, and temporal things are due to those who sow spiritual things. This debt concerns none but the clergy who have care of souls, and so they alone are competent to have this right.
On the other hand the things given in the name of tithes are material, wherefore they may come to be used by anyone, and thus it is that they fall into the hands of the laity.
Reply Obj. 1: In the Old Law, as stated above (A. 1, ad 4), special tithes were earmarked for the assistance of the poor. But in the New Law the tithes are given to the clergy, not only for their own support, but also that the clergy may use them in assisting the poor. Hence they are not unnecessary; indeed Church property, oblations and first-fruits as well as tithes are all necessary for this same purpose.