“Bible illustrations [parables] have more than one aspect. They … often have a prophetic meaning and application. Moreover, some had a prophetic meaning for the time when they were spoken or shortly thereafter, and some were to have, in addition, a fulfillment in the distant future.” (Insight on the Scriptures (1988), WTBTS, Vol 1, pp. 1176)
In the 10/1 1998 Watchtower study article titled, ''Jehovah, a God Merciful and Gracious'' there is a footnote that reads:
Parables and other illustrations related in the Bible did not necessarily take place in actuality. Furthermore, since the purpose of these stories is to teach a moral lesson, there is no need to seek a symbolic meaning in every detail.
In one breath they teach that the parables are not literal, but in the Matthew 24:45-47 parable, there are actual "faithful and discreet slaves'' on earth today. Why is this parable taken literal when others are not? How do they explain this one?