There is a conflict inherent in the "balanced" (more or less, in one or another form of the word) magic systems of roleplaying games and the way magic has been treated throughout the history of the European occult and cabalistic practices. The learning of spells and magic is, of course, abstracted in Dungeons and Dragons—understanding magic is linked to the level of the magic user. While many aspects of the game are reliant on player knowledge and player ability (particularly as it pertains to the OSR community), magic is one thing that must necessarily be abstracted. But there are certain things that we choose not to abstract. For example: the activation words for magical items I usually force my players to type out or say in our games.
This type of "player knowledge" magic is most successfully represented in Call of Cthulhu because that mythos magic is based on (at least in form and format) the occult practices of history. Performing a wizard's spell in D&D is a mental and intellectual act; the concatenation of mental construct and expressed notions (eg, the "memory-form" and then the "components"). Performing magic according to real historical traditions (which really only begin around the Enlightenment in non-cabalistic circles) is something anyone with the implements and the book can do. I haven't examined cabalistic magic in great detail, so it is possible that there are "memory-form" elements in Kabbala. There are not (as far as I know) in the derivative Sepharitic and Crawliest magics.
This means that if you have the book, can speak the names, and can draw the signs you can perform magic. That's more or less how it works in CoC—keep the formula and be able to perform the spell. I don't know how this can be applied to make better D&D... it's just something that I've thought about.