Although there was considerable liturgical uniformity in the first two centuries there was not absolute uniformity. Liturgical books were certainly being used by the middle of the 4th century, and possibly before the end of the third, but the earliest surviving texts date from the seventh century, and musical notation was not used in the west until the ninth century when the melodies of Gregorian chant were codified. The only book known with certainty to have been used until the fourth century was the Bible from which the lessons were read. Psalms and the Lord's Prayer were known by heart, otherwise the prayers were extempore. There was little that could be described as ceremonial in the sense that we use the term today. Things were done as they were done for some practical purpose. The lessons were read in a loud voice from a convenient place where they could be heard, and bread and wine were brought to the altar at the appropriate moment. Everything would evidently have been done with the greatest possible reverence, and gradually and naturally signs of respect emerged, and became established customs, in other words liturgical actions became ritualized.

The Lavabo or washing of hands is an evident example. In all rites the celebrant washes his hands before handling the offerings, an obvious precaution and sign of respect. St. Thomas Aquinas remarked: "We are not accustomed to handle any precious things save with clean hands; so it seems indecent that one should approach so great a sacrament with hands soiled." The washing of the hands almost inevitably came to be understood as a symbol of cleansing the soul, as is the case with all ritual washing in any religion. There were originally no particular prayers mandated for the washing of hands, but it was natural that the priests should say prayers for purity at that moment, and that eventually such prayers should find their way into the liturgical books. What prayer could be more appropriate than Psalm 25, Lavabo inter innocentes manus meas? All ritual grew naturally out of these purely practical actions, just as vestments evolved out of ordinary dress. The only really ritual actions we find in the first two centuries are certain postures, kneeling or standing for prayer, and such ceremonies as the kiss of peace, all of which were inherited from the Jews.

It is easy to understand that the order, the general outline of the service, would become constant almost unconsciously. People who do the same thing continually, naturally do it in much the same way. There was no reason for changing; to reverse the order suddenly would disturb and annoy people. The early Christians knew for instance at which moment to expect the lessons, when to receive Communion, when to stand for prayer. The fact that the catechumens were present at some part of the service, but must not see other parts, involved a certain amount of uniform order. But the prayers too, although there was as yet no idea of fixed forms, would naturally tend towards uniformity, at least in outline. Here also habit and custom would soon fix their order. The people knew when to expect the prayer for the emperor, the thanksgiving, the petitions. The dialogue form of prayer, of which we have many traces in this first period, also involves uniformity, at least in the general idea of the prayers. The people made their responses, "Amen," "Lord have mercy," " Thanks be to God", and so on at certain points, because they knew more or less what the celebrant would say each time. In a dramatic dialogue each side must be prepared for the other. So the order and general arrangement of the prayers would remain constant. We find in many cases the very same words used; whole formulas sometimes long ones, recur. This can be easily understood.

In the first place there were many formulas that occur in the Old or New Testament, that were well known in Jewish services. These were used as liturgical formulas by Christians too. Examples of such forms are: "Amen," "Alleluia", "Lord have mercy", "Thanks be to God ", "For ever and ever", "Blessed are Thou O Lord our God." Moreover it will be noticed that extempore prayer always tends to fall into stereotyped formulas A man who prays for the same object will soon begin to repeat the same words. This may be noticed in extempore preaching. The fact that since all early Christian language was saturated with Biblical forms means that it would hardly be possible for the bishop to use different words and forms each time he prayed, even if he tried to do so. And why should he try? So the same expressions recurred over and over again in the public prayers. A formula constantly heard would soon be considered the right one, especially as in some cases (the psalms and Lord's prayer) the liturgy already contained examples of constant forms. A younger bishop when his turn came to celebrate, could do no better than continue to use the very words (as far as he remembered them) of the venerable predecessor whose prayers the people, and perhaps himself as deacon, had so often followed and answered with reverent devotion.