From The Theology of Confirmation in relation to Baptism by Dom Gregory Dix. Dacre Press, Westminster 1946. (all emphasis in the original):
We know now, too, that the Apostolic paradosis of practice, like the Apostolic paradosis of doctrine, is something which actually ante-dates the writing of the New Testament documents themselves by some two or three decades. It is presupposed by those documents and referred to more than once as authoritative in them. This paradosis of practice continued to develop in complete freedom from any control by those documents for a century after they were written, before they were collected into a New Testament 'Canon' and recognised for the first time as authoritative 'Scripture' beside and above the Jewish 'Scriptures' of the Old Testament, which alone formed the 'Bible' of the Apostolic Church. Now that the history of the Canonisation of the New Testament is better understood, we can begin to shake ourselves free from the sixteenth century -- or rather the mediaeval -- delusion that primitive Christian Worship and Church Order must have been framed in conscious deference to the precedents of a New Testament which as such did not yet exist. The purely occasional documents now found in it do not contain, and were never intended by their authors to contain, anything like the Old Testament codes of prescriptions for the rites of worship. That was governed by the authoritative 'Apostolic Tradition' of practice, to which it is plain that the scattered Gentile Churches adhered pretty rigidly throughout the second century. I am not for a moment seeking to question the authoritative weight of the New Testament Scriptures for us as a written doctrinal standard. I am only trying to point out that there is available another source of information on the original and authentic Apostolic interpretation of Christianity, which the Scriptures presuppose and which must be used in the interpretation of the Scriptures. I do not deny that in time the recognition of this fact will be bound to lead to some considerable readjustment of ideas for more than one set of people. But tonight all I would say is that the liturgical tradition can be shewn to be older in some of its main elements than the New Testament Scriptures, and that down to the end of the second century, at least, it was regarded as having an 'Apostolic' authority of its own independently of them. We cannot look, therefore, for any attempt in this period to conform the practice of worship to them artificially. Nevertheless, the two do illustrate one another in a remarkable way.
I find the principle advanced here by Dix to be both compelling and fraught with implications. Its implications for the way in which most of us understand and apply the principle of Sola Scriptura are, despite Dix's demurral (I am not for a moment seeking to question the authoritative weight of the New Testament Scriptures for us as a written doctrinal standard), nothing short of revolutionary.