I often read discussions of Patristic citations that assume that, if two or more church fathers cite a passage a particular way, there must have been Greek manuscripts that supported that reading (even if none are extant today).
This seems to me to be a questionable supposition since there is often a strong oral tradition of citation that is independent of the what is written in copies of the scriptures.
I'm looking for examples, ancient or modern, of the phenomenon whereby, as in Casablanca (see title of this post), the way something is regularly cited is divergent from the original.
From the Rime of the Ancient Mariner we have:
'Water, water every where, and not a [original: Nor any] drop to drink.' (9,400 Google hits)
From the Bible we have:
'helpmeet' (Gen. 2:18; 'meet' belongs with the following phrase, i.e. 'meet for him')
'Our Father who [KJV: which] art in heaven'—has any Bible ever printed 'who art'?
There is also the case of the 'Rich Young Ruler'.
How common is this phenomenon? How common was it in the Patristic period and what criteria could we use to find out?