The plan of Tatian's diatessaron will account for a great deal.
Was his diatessaron such a book, or was it the Gospel according to the Hebrews?
There is a chronological synopsis, but no diatessaron table.
And thanks to modern discoveries, especially that of the diatessaron, this is now generally admitted.
A large discount has therefore to be made from the agreements between diatessaron and Syr.
Probably the maker of this version was partly guided, especially in his choice of renderings, by his knowledge of the diatessaron.
Here we get the diatessaron identified with the widely-spread and popular early Gospel of the Hebrews.
But there is not yet the same degree of consensus as to the relations between the Old Syriac and the diatessaron.
Some suggest that he knew John's order and preferred it, others that he agreed with that adopted by Tatian in his diatessaron.
The 'diatessaron' has been long lost, and the name is the only clue to its composition.