Exegesis:

ouk oidate tēn parabolēn tautēn; ‘do you not understand this parable?’: as a question, this is purely rhetorical, since it is not a request for information, but stands as an accusation. It may be taken as a statement, however: ‘You don’t understand this parable! How then…?’ Or it may be taken as a condition: ‘If you don’t understand this parable … how will you…?’ (cf. Goodspeed, Berkeley, Williams).

oidate … gnōsesthe ‘you know … you will know’: it is precarious to try to maintain a strict distinction between oida ‘know by intuition or insight’ and ginōskō ‘know by experience or observation’ as do Swete, Taylor. oida occurs some 23 times in Mark and ginōskō 12.

Translation:

Note that the direct discourse may consist of questions, in which case the introductory verb must often be ‘questioned’ rather than ‘said.’ On the other hand, the first expression may be a statement (see above), followed by a question. In any event the questions are strictly rhetorical, and if such questions are treated in any particular manner in the receptor language this fact should be consistently indicated.

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 .