Mage Ascension 20th Anniversary rulebook is a huge, 700 page doorstop and it's filled to the brim with rules, descriptions and more or less poetic game aids. It is my perception that even for GMing some sections of the book can be skipped without harming the game too much (like the elaborations on Technocratic practice designed for Union PC's).
When I'm playing my next MtA campaign I'm extremely likely to have mostly players who have only heard rumors about Mage and never even seen or played World of Darkness game. This means that they will have to learn the basics of Mage one way or the other.
The best way of familiarising someone with Mage basics quickly is in my opinion the Quickstart Edition, which conveys most important game-enabling information in a compressed form. Of course, once the player is through the QS, it still does not give him enough knowledge of the game to actually play it. I expect the players to request more information about Spheres, Traditions and maybe some character-specific concepts.
However, I feel that some concepts are mentioned only vaguely in the QS while they are central to the player's understanding of what happens in any Mage game: that's mostly with regard to Paradigm, Focus, Consensus, Coincidental and Vulgar magic, Paradox, Quintessence and Will. Character Creation chapters of course have to be available for the players and while specifics can be showed upon request, introductory chapters should be read by everyone, including bits about Avatars.
What other minimum information does a player need to successfully participate in a MtA game without unnecessary interruptions?
Which sections of the rulebook should be given to the player to read?
A couple points for answerers:
I assume players will read provided material, but I hope it would be compact enough not to cause any grumpiness.
I assume players have no prior knowledge of World of Darkness or Storyteller/Storytelling systems or any other related WW/OPP product.
I also assume that reading in own time is the best solution - teaching at the table and writing/finding chapter summaries is out of scope unless absolutely necessary.
I assume minimal campaign, operating only within the basics of the game. I know that every game (and character) has different needs. Shamanistic Dreamspeakers would need to get a good grip on Umbral cosmology, Virtual Adepts will probably want to know about the Digital Web and campaigns featuring Marauder NPCs will require solid knowledge on Paradox and Quiets. These are treated as addendums and not the scope of the minimum as I understand it.
Finally, if reading some other source material for 20th Anniversary, e.g. VtM intro chapters would be useful, I could consider it as well.