lol.
That is barely a quarter of the sentence they said.
What was
unknown before eating that could only be known after eating?
Knowledge?
He/they had already told the students what they needed to
know earlier. He/they had described the tree as of ,,,,,,,,
knowledge,,,,,,,,,,,,,,,of,,,,,,,,,,,good and evil.
By being told that the students hence already '
knew'.
The gist was in the students' (I hope I got the apostrophe right) ability to obey his / their express command. Eating hence implied disobedience and distrust.
So, yes He/they mentioned something about acquiring knowledge, illumination, enlightenment from this specific, particular, singular instance of eating.