I see. If you are unsure, the game does include a HELP command, as well as a HINT command too that will give you either hints or the solution for those puzzles (should be indicated in the Intro). There is also a downloadable walkthrough (and the Map!) if you need it :)
But there's some hints:
- Icarus won't leave until you deal with another NPC and tell him about it
- If you listen to Eriboea, and ask her about the word she is repeating, you'll trigger the puzzle.
Hope this helps!