Spirit of the Liturgy

Extract from Athanasius Contran Mundum (Emphasis my own)

One of the things trumpeted by champions of the reformed rites is that now the priest is free to "express himself". Now, that rigid rubrics have been tossed aside, the priest can be himself, and share himself with the congregation. All that is necessary is to go to Mass each morning and encounter your parish priest shouting out "Good morning everybody", at an act that is supposed to be the holiest thing we can encounter....

[In the Traditional Mass,] there are set and defined rubrics. The priest faces the altar, he needs to perform certain rituals at certain times, and make certain steps in certain places. The priest in the Traditional Mass can not decide he is going to add his own flavor, he can't substitute a hymn for the parts of the Mass which will be said by every priest praying that missal in the world. Rubrics are present at the Mass because the priest stands in persona Christi. He is not himself. He is Christ. There is no better way for the priest to conform with Christ than to die to himself, as our Blessed Lord did on the cross. Jesus without resistance, though it was in his power to do so with terrible effect, laid down on the cross and offered up his life as an act of love, to make propitiation for our sins. When the priest stretches out his arms, he does as Christ who stretched his arms on the cross for men. In as much as the priest does not deviate from the rubrics, he dies to himself. Facing the altar and consequently God, he performs nothing. Rather one could say correctly that he surrenders himself so that what the Church always and every does is accomplished through him.