Garrow, Alan J.P. "Chapter One: Introduction." The Gospel of Matthew's Dependence on the Didache. New York: T&T Clark International, 2004, 1-8.
Garrow relates the Didache to a map which, when discovered, appears valuable, but which is of only very limited usefulness due to the lack of a key. The time and location of composition, as well as the question of literary dependence were uresolved, thus leaving the work without meaningful and necessary context. Garrow's plan is "to present a detailed map of the relationship between Matthew's Gospel and the Didache." (Garrow 2004, 2).
The Didache has been considered to have a date after Matthew's Gospel due to its manuscript location among Apostolic Fathers and the "four references to 'the gospel' (8.2b; 11.3b; 15.3-4) amid, in the case of 8.2b especially, the passages that relate closely to Matthean material" (Garrow 2004, 3). This second argument has a fundamental weakness, since the Didache is widely considered to have undergone several layers of redaction, so these statements may not have been present from the start. Garrow summarizes his counter-argument to be "a relatively simple explanation of the two texts' relationship: namely, that various elements (disparate in terms of style, origin and age) were incorporated into the Didache over time and that, at a later date, Matthew drew on the resulting text in the construction of his gospel" (Garrow 2004, 4-5).
In Garrow's opinion, the redactional history proposed by other scholars has always presupposed the pre-existence of Matthew. This has skewed the scholarly consensus on the dating of the Didache, while it has also created some difficulties, such as requiring that different redactors would have used material in the same way as each other (Garrow 2004, 6). It also suggests that Matthew and the Didachist repeatedly gathered material from the same version of the same tradition. This strikes Garrow as unlikely (Garrow 2004, 7).