Exegesis:

de ‘but,’ ‘and’: as Taylor says, it is impossible to dogmatize whether the particle is here adversative ‘but’ or explanatory ‘for.’ The interpretation of the saying is vitally affected by the question. Almost without exception commentators and translations adopt the adversative meaning ‘but’; Lagrange, however, understands it to mean ‘for’ and thus interprets the saying.

prōtoi ‘first’ and eschatoi ‘last’ probably refer, not to time, but to rank, as in 9.35.

Translation:

First and last in such a context as this are highly abstract terms (compare the usage in 9.35). In Huautla Mazatec first and last must be shifted to the figure of a line of men, e.g. ‘he who wants to be placed first will follow.’ A similar figure exists in Chicahuaxtla Triqui ‘those in front will go to the rear.’ In Copainalá Zoque the same figure is employed ‘first ones go behind and the behind ones go ahead.’ In some instances, however, the contrast must be related to importance, e.g. ‘the greatest’ (Highland Puebla Nahuatl).

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .