Historic historian at that, his work on the Mass a classic, here in general terms about change/reform early in his Mass of the Roman Rite: Its Origins and Development:
The liturgy of the Mass has become quite a complicated structure, wherein some details do not seem to fit very well, like some venerable, thousand-year-old castle whose crooked corridors and narrow stairways, high towers and large halls appear at first sight strange and queer.
How much more comfortable a modern villa! But in the old building there is really something noble. It treasures the heirloom of bygone years; the architectures of many successive generations have been built into its walls. Now these must be recovered by the latest generation.
So, too, in the Mass-liturgy, only a historical consideration of the evolutionary work of the centuries can make possible a proper appreciation.
One of a series of references to this work, with a view to understanding what went into the reform of the Mass — or was meant to go into it, as the case may be.