A snip from a late 1980s interview with Fr. Wathen on this subject.....
Question: As far as there are three main parts of the Mass, am I right? There’s the liceity, the morality and the validity. Would you explain each of these and give a little explanation of each of these in their different areas.
Fr.When you use the word liceity you’re referring to the question of whether the new mass is legal.
When you speak of validity, you are discussing whether the consecration of the mass is valid and true, whether there is truly transubstantiation.
When you discuss the matter of morality, you are questioning whether it’s a sin either to offer the new mass or to attend it.
I hasten to say that if the new mass is against the law, then it is immoral, and if there is a question of validity in the consecration, then it is immoral for anyone to use it.
Question: You believe it’s actually a sin, a mortal sin to use the new mass, is that not right?
Fr.That’s right. We believe that because the new mass is clearly against the law which governs the liturgy of the Roman Rite, that there is no legality to it - and we think that to violate the law with regard to the True Mass there is a moral violation, we believe that is a grievous violation, and therefore a sacrilegious violation of the True Mass. It is most important for people, when considering the new mass, always to bear in mind that the Traditional Latin Mass, which is to be found in the Missale Romanum of Pope Pius V, that, that is the standard whereby they judge any other Rite in the Roman Rite.