The prophet is a mantic when he predicts e.g. the punishments the Lord will inflict upon His recalcitrant people. He is a pedagogue when he exhorts his people telling them how to better their ways so that they may be spared the wrath of the Lord.
The terse phrase "The oracle remains ambiguous" seems to have been added as an afterthought. I read it as follows. A prophecy is unambiguous though being mantic and pedagogical at the same time. If you do this, the Lord will do that; if you do that, He will do this. So you'd betterÂ…The oracle, on the other hand, though also prophesying and speaking true, is obscure and can be misleading. When Croesus, King of Lydia, asked the Delphic oracle whether he should start a war against the Persians. The answer was, if he did he would overthrow a great empire. Croesus believed the oracle meant the Persian empire, but it turned out to be his own that was destroyed when he was defeated by Cyrus. (Herodotus, HISTORY, I, 53).
