Medieval calendars quite often inform us that the Sun is in the constellation Virgo on August 15. I wonder if it has ever been suggested that this astronomical fact has anything to do with the selection of that day to celebrate our Lady's Assumption.
Which Collect is preferable on August 15? Certainly not an Anglican one: they all seem rather sad examples of modern Anglican collect writing: a couple of wordy banalities shoved together, and all the time a sense that the writer is looking over his shoulder fearing that he might be deemed too "extreme". The Pius XII composition is preferable ... but I'm not over-enthusiastic about it quite simply because one of the older collects it replaced is, in my view, quite exquisite. I don't see how anybody whose affections are excited by the old collect Veneranda, and by the teaching of S John Damascene, and the explicitness of the Byzantine Liturgy about the glorification of Mary's wholeness, can dislike the Pius XII collect for doctrinal reasons. But minimally conceived 'doctrine' does not exhaust the content of 'Tradition'.
My own hesitations about features the 1950 definition relate not to what it said, to which I of course very cheerfully subscribe ex animo, but (1) to what, by not saying, it appeared to imply could be forgotten - such as the edifying common legends which informed piety and art in East and West for centuries and about which Blessed John Henry Newman spoke so sympathetically; and (2) to the fact of our Lady's mediation of all graces. This was clearer in the older traditions of East and West, but in the West has more recently been overshadowed by preoccupation with the idea, true in itself, that the Assumption is the logical consequence of her preservation from all sin.
Mary, in History, mediated all graces to humankind by giving birth to the Redeemer; her Assumption means that what she was in History she is ontologically and for all eternity. In her, function and ontology are fused into one.
I would feel more cheerful about the 1951 liturgical texts if they could be supplemented by a definition of our Lady as Mediatrix of All Graces. It could be phrased in the elegant Greek with which S Gregory Palamas explained this truth! Pius XII, for all his Marian devotion, was opposed to the concept of our Lady's Universal Mediation. Now is the time for Pope Francis to recalibrate the balance!