Priests and Wizards as separate classes

[Frozen_Feet]

I see a lot of "D&D did it", but very little proper analysis of why D&D did it. It had nothing to do with Vancian magic, as one should guess from the fact that Magic-Users and Clerics both use the same system.

Instead, the divide existed along two lines: white magic versus black magic, and faith versus science.

The first should be obvious. In earlier editions, Cleric magic focused around healing, protecting and supporting others. Magic-User Magic focused around destruction, curses and helping yourself. It's also obvious when you look at summoning spells of the respective classes - Clerics summoned animals, spirits and angels, while Magic-Users summoned undead, demons and lovecraftian horrors.

The second is related to why Clerics use Wisdom and Magic-Users use intelligence. I examined this in-depth in this post. The Clerical stereotype comes from Knight Templars and western monks, to which servitude to a higher cause and moral righteousness were defining features. Moral righteousness, especially, has been associated with wisdom in... pretty much every culture, and is often contrasted with "cold logic" or some such. In short, Clerics are spellcasters who follow their good heart over their brain. If you want evidence, just go over the original Cleric spell list and count how many are directly inspired and even named after biblical miracles.

Magic-users, on the other hand, draw their inspirations from witches of folklore, of alchemists of middle-age and renessaince, and Renessaince men like Leonardo Da Vinci who could do a bit of everything and pioneered many inventions and scientific concepts. They are defined, somewhat, by their inviduality and opposition to established worldview, like the Church. They are the ones who go where no man has before, and reveal secrets no man was meant to know. In contrast to Clerics, they represent dominion over natural forces, rather than servitude to them. They follow their brain instead of their heart. This reflects in their spell lists, which are full of scientific and pseudo-scientific jargon and in-jokes.

Later editions have screwed up blurred these distinctions, however, through absorbing influence from more and more different mythologies where these distinctions were never made. MU dominance over black magic vanished quite rapidly through introduction of the Anti-Cleric and reversed spells. Then the scientific outlook of MUs took a hit when many setting introduced a God of Magic. The 3rd edition addition, the Sorcerer, is basically a step back towards folkloric wizards and witches, who communed with spirits and bend them to their will through force of personality, rather than analytical thinking. Pathfinder took this further by making the Witch one of the baseclasses. 4th edition in turn made an effort to make a class for each and every different way to look at magic, with mixed results.

Non-D&D RPGs are all over the place when it comes to this issue. Many only buy into one of the above-mentioned dividing lines, but not the other. In many settings, all magic is mystical and beyond scientific inquiry, but different classes still exists for black magic and white magic.