Ability Scores and Casting - Intelligence

Intelligence as a casting stat is a much better fit than Wisdom, based on the idea that a Mage or Wizard needs to be able to understand and remember the arcane formulae used in their version of magic. My main complaint here is that Intelligence is used solely for both the number of spells an arcanist may know as well as how many can be cast. In most literature on the subject, it seems that using magic, channeling the power either through or from your body, seems to have a physical impact on the magic user. Raistlin, for example, though he's hardly the only one. Even Miyazaki's Howl had physical difficulties when performing more powerful spells.

My solution to this is rather simplistic: keep Intelligence for the number of spells known or learnable, but make Constitution govern the number of spells that can be cast. In retrospect, perhaps a similar thing could be done for divine magics, keeping Wisdom for the number of spells known, and Faith for the number that can be cast, to correlate with the idea that the power comes from the deity, while the cleric is responsible for applying the power through the proper use of the spells/prayers/whatever gained from reading their sacred texts.

On second thought, however, this works well for Clerics but not necessarily so aptly for Druids. Druids, as a part of Nature, seem to draw their energy from it or from within, so they seem more closely related to Mages in that manner. Perhaps Wisdom (knowledge of the cycle of life and nature) to determine spells known, and Constitution to determine spells per day.

3rd Edition Sorcerers are a strange creature. Per the way 3rd edition spellcasting seems to work, Sorcerers should, even moreso than Wizards, have their Constitution determine the power available since it is stated that their power comes directly from within, rather than channeling latent power through the use of mystic formulae. WotC explains this as being due (possibly) to dragon blood somewhere in the lineage of the Sorcerer, citing some Force of Personality as being the power behind the spells. Yet none of this really seems to indicate how or why Charisma should determine the number of spells known. It seems that Sorcerers learn through trial and error what they can and cannot do, mostly learning Wizard spells since those have a known effect that they can try to reproduce. Sorcerer as a class really doesn't have anything going for it in 3rd edition. A specialized Wizard could cast the same number of spells, have more powerful ones available, and even get some free metamagic feats, whereas a Sorcerer actually sacrifices effectiveness with the feats, and only gets a piddling amount of extra weapons to choose from, none of which are necessary or even desirable to most people. I think I'd just as soon drop the class entirely.

Bards are odd, as well. They actually have enough difference to stand as their own class, rather than being a variation of something else, but again they're Charisma based casters, and again there's nothing that explains why Charisma, whether it's Personality, Leadership, Beauty, or whatever, should have an effect on the number of spells known. At least Bardic Tradition, whether it's passed on from one generation to the next or learned at a Bardic College, can explain how those spells are learned, but I would almost think that Intelligence, serving in its capacity as Memory, would govern what a Bard could remember and cast.

Well, I've gone beyond Intelligence here. Let's sum up.

Clerics: Gain spells from Wisdom, gain power from Faith
Druids: Gain spells from Wisdom, gain power from Constitution
Wizards: Gain spells from Intelligence, gain power from Constitution
Sorcerers: Are silly
Bards: Gain spells from Intelligence, gain power from Charisma

As always, comments are welcome, and constructive criticism encouraged.