>>40679398
The oldest degree system that I'm familiar with is the Mithraic order, but I don't think that's the authoritative source. Mithraic stuff seems like a knightly brotherhood, so I guess you could call it a soldier's guild.

I think temple = school = guild in some cases, so we can look for the origin of any of these things and find ancestors of cousins of the concept. That would take me to Egypt or maybe Babylon. The book I read on this was incredibly biased, but it seemed well-researched. It talked about how guilds were below the temples of the major god(s) in town, but it opened an avenue for the middle class to gain power in an unchecked manner. They started running their temple as a business, asking for favors/money and building a network with other merchant guilds in other cities.