Correlative with the obligation of rest is that of purely positive worship, and here is the difficulty of deciding just what is the correct thing in religious worship. The Jews had their institutions, but Christ abolished them. The Pagans had their way--sacrifice; Protestants have their preaching and hymn-singing. Catholics offer a Sacrifice, too, but an unbloody one. Later on, we shall hear the Church speak out on the subject. She exercised the right to change the day itself; she claims naturally the right to say how it should be observed, because the day belongs to her. And she will impose upon her children the obligation to attend mass. But here the precepts of the Church are out of the question. The obligation, however, to participate in some act of worship is plain. The First Commandment charges every man to offer an exterior homage of one kind or another, at some time or another. The Third sets aside a day for the worship of the Divinity. Thus the general command of the first precept is specified. This is the time, or there is no time. With the Third Commandment before him, man cannot arbitrarily choose for himself the time for his worship, he must do it on Sunday. Public worship being established in all Christian communities, every Christian who cannot improve upon what is offered and who is convinced that a certain mode of worship is the best and true, is bound by the law to participate therein. The obligation may be greater if he ignores the principles of religion and cannot get information and instruction outside the temple of religion. For Catholics, there is only one true mode of public worship, and that is the Sacrifice of the Mass. No layman is sufficient unto himself to provide such an act of religion. He has, therefore, no choice, he must assist at that sacrifice if he would fulfil the obligation he is under of Sunday worship. CHAPTER LI. WORSHIP OF SACRIFICE. WE Catholics contend, and our contention is based on a law of nature that we glean from the history of man, that sacrifice is the soul of religion, that there never was a universally and permanently accepted religion--and that there cannot be any such religion--without an altar, a victim, a priest, and a sacrifice. We claim that reason and experience would bear us out in this contention, even without the example and teaching and express commands of Jesus Christ, who, in founding a new and the only true religion, Himself offered sacrifice and left a sacrifice to be perpetually offered in His religion; and that sacrifice constitutes the high worship we owe to the Creator.