(As regards comments, see the first part of this.)
The great Christine Mohrman pointed out the juridical nature of Christian liturgical Latin, and showed that it was in direct descent from the pagan cultic Latin used in the centuries ante Christum; for example, in the Prayer asking the Gods of a city under siege to leave it ... to leave the city and its homes and temples and streets and ... The principle is to cover everything and leave nothing out. So, in our Quam oblationem Prayer, the priest asks that our offering may be "on the list"(adscriptam)!! For a Mass to be valid, one realises, it must be on God's official list, just as there is no point in turning up at Heathrow and asking for a Boarding Pass unless your booking is in the computer. God must have said the OK to it (benedictam). Bene-dicere (literally, "to say well") is a verb closely linked in Biblical Latin to the idea of God "looking with favour" on an offering ... that is, accepting it. Consider Genesis 4:4-5 ... Respexit Dominus ad Abel et ad munera eius. Abel, not surprisingly, is cited in our Canon as a precedent for divine acceptance. And so the Secret for Dominica VII post Pentecosten says: Accipe sacrificium a devotis tibi famulis, et pari benedictione, sicut munera Abel, sanctifica. In other words, while the Epiclesis I quoted at the beginning from the liturgy of S James made itself rather lengthy by citing divine precedents for the sending down of the Spirit to work mighty change, the Roman Canon is content simply to mention the Biblical 'typological' precedents for divine acceptance of human Offering. Ratam ... acceptabilem make the same point about divine acceptance and ratification ... just as when you enter the USA and the Homeland Warrior asks penetrating questions about your motives for trying to do so ... this even happened to a son-in-law of mine who has American citizenship ... and then reluctantly stamps your passport making you ratus and acceptus. Rationabilem relates to the Sacrifice as logiken rather than cruentatam but, none the less, acceptable.
It is not my purpose to discuss which of these attitudes is preferable, although I will admit to a strong preference for the theology of the Roman Canon, just as I would expect an Oriental Christian to feel most at home with the Eastern approach. There is a sense in which I would even agree with the idea that Diversity is essential to Catholicity! What I do wish to highlight is, quite simply, that they are different. And that they can't just be taken into the kitchen and shoved into the blender and mixed up. One of the very few things I object to very strongly about Orthodoxy is that it sanctions 'Western Rites' in which an Oriental Epiclesis has been violently shoved into the Roman Canon. I would complain with no less vigour if some daft Latinising imperialist tried to mangle or eviscerate an Eastern Anaphora. Each of our rites has its own integrity, its own logic, its own grammar. Neither should be bullied into conformity with the other. To do so ... I would go so far as to call it sacrilege.