The idea that magic strips the knowledge from your brain, but not the knowledge that you have the knowledge written down in your handy dandy spellbook is IMO, dumb.
Here is my answer to that issue:
[sblock=I am crazy]WIZARDS AND SPELLS
SPELL is an arcane term for the controlled energy of creation. A usable pattern forms through the study of the raw elements of creation - a way of thinking that allows the caster to create something out of nothing. The mortal mind cannot understand the ineffable mysteries of true creation; spells are the only way wizards have been able to tap into that vast power. They involve chants, mantras, ritual movements, self-hypnosis, fasting, and mind-altering drugs: anything that allows the wizard to expand his consciousness enough to grasp the true nature of reality.
There are three types of spells: cantrips, minor, and true spells.
Sidebar: Wizards
These rules are meant to add flavour and colour to the wizard class. They bring the wizard in conflict with the setting, not only because he needs to explore to find new spells, but also because he needs time away from any interruption to prepare them./sidebar
PREPARING SPELLS
Think of trying to see the universe, in its entirety, in one single glimpse of insight - and comprehending it. That's what a wizard does when he prepares spells.
You can memorize a number of spells equal to your Intelligence (indeed, anyone can); some wizards scribe their spells into spellbooks to avoid having to keep every spell memorized at all times. These grimoires are jealously guarded by their owners.
Simply knowing the spell is not enough, however. A sage may have a hundred spells in his grimoire yet be unable to cast the simplest one. Before you can cast the spell, you must bring it into being - a pattern of energy caused by thought, held within your mind. You need to put yourself into strange and exotic mindsets to force a spell into being. Only a few of these spells may be contained in your mind at any one time without driving you mad; this is represented by the number of spells you may cast in a day.
Forcing a spell into being is a time-consuming process, requiring you, through ritual, study, and alchemy, to alter your perspective of reality to match that of the spell. Each wizard has his own, idiosyncratic method of altering his perception; some wizards require quiet meditation, some use mind-altering psychotropics, and others use intensive study. Decide what your own method is at character creation.
You must spend 6 hours per spell you wish to prepare; during this time you may take no other actions and gain no benefit of rest. Any interruption during this time spoils your concentration; you must repeat the process from the beginning. You may prepare the same true spell more than once, as long as you don’t exceed the total number of spell slots available, using slots of the spell's level or higher and of the same type.
Preparing Rituals: You can prepare a ritual you know, just as though you were preparing a true spell. It requires the use of a true spell's slot of the ritual's level or higher, 6 hours of ritual preparation, and the expenditure of the ritual's components. At the end of this period, you have prepared the spell. Note that any extra time required by the ritual (such as drawing the runes of a protective circle) are still necessary.
CASTING SPELLS
Casting a spell: You merely need to speak - loudly and clearly - a Word of Power when you want to release the spell’s energy. The spell takes form and becomes real, and you guide it to fulfil your wishes, within the parameters of the spell. There is usually no difference in casting spells of different types, the difference lies in what happens to the spell after it is cast.
Cantrips: When you cast a cantrip, you do not need to release the spell from your mind. The spell remains prepared. You may loose a cantrip from his mind at any time. Replacing a cantrip with another takes a week, during which you cannot adventure, rest, or prepare other spells.
Minor Spells: More powerful than cantrips, when cast, a portion of the spell is released from your mind. Restoring the released portion is relatively simple for an experience wizard, however; you need only spend five minutes of ritual preparation, during which you can take no other actions and gain no benefit of rest.
You may loose a minor spell and replace it with another as he does with cantrips, above.
True Spell: True spells are the most powerful. The power released when the spell is cast wipes it from the wizard's mind. No trace of it is left, and the wizard must prepare it again.
ECCENTRICITIES
Spells are slippery things. When you force a spell into being in your mind, the spell exerts its own will on you! This can be hard on your mental state, which is why many old and powerful wizards are considered mad. Most wizards know their limits - the number of spells they may have prepared in any one day - but some seek to break these.
If you go past this limit, you give a part of yourself over to the spell, and it can control your mind.
Eccentricities Table
What happens to you when you break your limit
Per extra spell
This would be an "interesting event" list
Must be crazy, enough to cause problems even during down-time, but not so crazy as to make it a never-selected option
WORDS OF POWER
Though the primordial power of creation cannot be expressed in language, some mortal (and immortal) beings have attempted to describe it. Wizards do not need to be fluent in this language in order to cast their spells; merely a word or two associated with the spell will do. Fluency helps, however, and can provide a situational bonus to checks when researching new spells or when casting rituals.
LEARNING NEW SPELLS
When you gain levels, you do not learn any new spells! You must adventure or study and research in order to expand their repertoire of spells.
You may learn new spells from long-forgotten tomes of knowledge, from grimoires taken from defeated opponents, or through experiment. Learning a spell from a book or scroll requires 4 hours of study per spell (during which time no other actions can be taken and the wizard gains no benefits rest).
Creating new spells requires a week of experiment and requires arcane alchemies. See the chapter Character Growth for more.
FEAR OF MAGIC AND WIZARD'S ASYLUMS
Most people fear arcane magic. The strangeness of the world terrifies those who do not have the power to control it and cannot understand it. To them, wizards seem less-than-human, with their eccentricities, strange alchemies, and rituals. When a wizard prepares spells in a settlement, the villagers become uneasy. Many wizards have been driven from the safety of a town's walls because of superstition.
Because of this, most wizards with the means create an asylum (or seclusium): a place where they can be left alone to study, research, and prepare in peace. The ruins of these places still dot the land, and much of the owner's research can still be found.[/sblock]
edit: I've been working on this tonight.
