Question about Parable version criticism

What are the 'usual rules' for arguing that a 
given version of a text is older than its variants?

I'm looking at several of the parables given in the
Gospel_of_Thomas (from Nag Hammadi; logia #9, 20, and 64, for

In the translation of _GT_ given in Three_Gnostic_Gospels
(I no longer have a copy, & it's OOP, alas!) the translator argued for 
the priority of some of the GT versions, relative to the NT versions.
I'm just trying to reconstruct his argument.

The things to look for (that I can think of) would be:

	- 'precision' rather than 'expansion'
		(Mark 8:12 vs. Matt 12:39, Luke 11:29)

	- 'Aramaicisms'

	- more specific vs. more abstract
		(Matt 6:20 ('no thief breaks/digs through')
		[Gr.'diorusso'] vs
		Luke 12:33 ('no thief approaches')

(If this is not generally interesting, even as a tutorial,
then e-mail me rather than post to the whole list. Pointers
to references are especially welcome). 


Dave Davis


"Become as passers-by."
		Gospel_of_Thomas, attr. to Jesus