Let's say you have heard all kinds of prog. Please divide them into 6 levels and explain the "entrance work" for each level.
example:
Level 1 - College Freshman
entrance work: Dark Side of the Moon
explanation: The most famous album of all, doesn't even take a proghead to appreciate it.
Level 2 - College Sophomore
entrance work: In Absentia
explanation: the most acclaimed studio album by the leading progressive rock band today, it will introduce you to darker and more sexual concepts.
Level 3 - College Graduation Project
entrance work: Cynic - Focus
explanation: Time to hear some harsh/growled vocals and extreme techniques. Focus on this and you will get your Bachelor degree in due time.
Level 4 - Graduate School
entrance work: Frank Zappa - pick 3 albums
explanation: You are trained enough to embrace this genius.
Level 5 - Master Degree
entrance work: Terria
explanation: thick and industrialized, what better album to show you yet another Dark Side of the Prog?
Level 6 - PhD
entrance work: Close to the Edge
explanation: If you can publish an essay on this symphonic masterpiece, congratulations, you are a Progfessor now (or Close to the Edge of being one)
I'm personally at level 3 right now. Haven't got the Bachelor degree yet.
Now try to outdo my list.