Oral tradition and the use of "Καὶ" ("And")
Right from the beginning Schmidt claimed an oral tradition of little Jesus stories as a fact and explained it with regard to one of Mark's most recognizable stylistic features: the frequent paratactic use of the word "And
Ron Decker wrote
Perhaps the most distinctive feature of Mark’s idiolect is his paratactic style, stringing sentences together with καί rather than more specific conjunctions ...
Mark’s usage can be quantified in various ways. Metzger, e.g., observes that 80 of 88 sections in Mark begin with καί. Another way of illustrating Mark’s parataxis is noting that about 64% of the sentences in Mark begin with καί (376 of 583). A more limited snapshot can be seen in taking Mark 1 as a sample and comparing it with the sections in Matthew and Luke which are roughly equivalent. Of the 38 sentences in Mark 1 (UBS4), 33 begin with καί. By contrast, Matt 3-4 contain 34 sentences, but only 9 begin with καί. Luke 4 has 31 sentences, of which 23 are καί initial.
This does not mean that Mark is characterized by pervasive asyndeton (on which see below), only that he does not write hypotactically - he does not make very extensive use of the various particles available to him.
For Mark, all is καί - the unmarked connective ...
And here comes Schmidt (google-translated from German)
The first story (GMark 1:4-8 John the Baptist) used by Mark in his gospel began with "Καὶ ἐγένετο" - "And it came to pass". It may seem strange to claim that the first pericope just began with "καὶ".
Comment: Schmidt did not mean that the original reading of Mark 1:4 was "And it
came to pass". He agreed that Mark just wrote "It
came to pass" ("ἐγένετο"). However, his claim was that the oral story that is the supposed source behind Mark 1:4-8 began with "And it
came to pass".
This introduction (GMark 1:1-3) represents a literary work such as could not have been contained in the mouth-to-mouth accounts of the history of Jesus. It comes from the evangelist, that is, the man who united the individual stories into a whole.
Note that Schmidt considered oral tradition dogmatically.
The stories from the history of Jesus went from mouth to mouth in the early days. When the Christians were together, they told one another the words and deeds of the Lord, one replacing the other, one supplementing the other. And even if the Jewish Bible was the holy book in the worship gatherings, everything that was known to be said about Jesus must have played an important role from the outset.
Nonetheless, Schmidt was aware of his dogmatical claim but he chose to blindly follow his assumption.
We don‘t know anything definite about these things. But we cannot imagine vividly enough such talking and telling about the story of Jesus within a circle of storytellers, within the cult community. Anyone who makes the necessary attempt to visualize the first period of the Gospel tradition cannot do it without the hypothesis, which he knows cannot be developed into infallible proof, but which helps us to understand things and at least as a whole historically correct.
Hermann Detering would say that the Bible scholar Schmidt became here an oriental storyteller who embellishes his fairy tales with many invented details.
In an informal exchange, one Jesus story was lined up after the other. When one had finished reporting, the other continued with "and it happened that ...".
In this way complexes of several stories were created, which were separated from each other by a mere "καὶ". “καὶ” or the Aramaic correlate became a caesura, a caesura of the most primitive kind. It is possible that such complexes were written down for use in worship, in order to read several stories one after the other. But then again only a story, a pericope, was presented. The "καὶ" remained, just as we read the Sunday gospel in our churches today and start with an "And". Despite all this, the individual stories continued to pass from mouth to mouth, and even then the "καὶ" remained. Finally the Evangelist came, who collected the individual stories and tried to bring them into context. Even then, the "καὶ" remained in many instances.