Magic Is Mental

"Don't look at me like I'm going to shoot lightning from my fingers or summon the Devil. Or worse, like I think I can. Magic is a psychological discipline."

—Alan Crowe, magician, Global Frequency

A trope that is nearly omnipresent when magic is involved: Magic is a product of the mind, not the body. Magic requires study and concentration to use. The best mages are smart, wise, perceptive and are all around great minds. It's even in the word "Wizard" which used to mean "Philosopher" and came from the word "Wise". The word magic itself descends from magos "one of the members of the learned and priestly class". It's not accidental wordplay that forces you to learn basic spelling before you can study spellcasting.

As such, this trope has many, many consequences: In an ensemble group, those with magics will tend to be the smartest. They are the most well-learned, those who have studied and are the wisest. They will be The Smart Guy.

In games with stats, magic is often related to a "mental" attribute if it's not its own, segregated attribute. Popular choices are intelligence/smarts/logic, willpower/wisdom/spirit or charisma/personality. Different types of magic may require different attributes, with Hermetic Magic favoring the first, and divine magic favoring the second.

This trope is why we have Squishy Wizard - magic requires a strong mind, not a strong body, and this is the handwave often used.

Often, Asian works follow the trope less rigorously, with magic being shown as a product of both mind and body. Thus seeing character study, train and combine magic with martial arts is not rare.

Related to Enlightenment Superpowers. See also Ritual Magic which may involve a lot of memorization and concentration. Not to be confused with (but might coexist with) Power Born of Madness.

Examples of Magic Is Mental include:

Comic Books

Comic book characters using magic (especially the wizard kind) often are intellectuals. Notably, DC Comics' Doctor Fate and Marvel's Doctor Strange are two spellcasters with the title of "Doctor", which itself implies a level of education (e.g. Doctor Strange was a neurosurgeon and his successor, Doctor Voodoo, was a psychologist).
- Strange in particular has mentioned that spellcasting requires a strictly disciplined, focused mind. "If you do not pay the utmost attention, magic can get away from you in a heartbeat. Every spell, every sigil, every manipulation... you must keep a close eye on everything so it doesn't backfire."

Literature

In Discworld, wizard-magic is based on knowledge (the three known wizarding universities are the Disc's centres of pure learning, compared with the vocational schools run by the guilds), and witch-magic is based on force of personality. (In D&D terms, Intelligence and Charisma.)
In The Imager Portfolio by L. E. Modesitt, Imagers use their 'magic' completely with their minds, by seeing/imagining them in their heads, but they have to have a complete mental picture and understanding of it's elemental and chemical make up or they can do things like blow themselves up by mixing chemicals which react explosively with each other. They also can image in their sleep as they dream, so they have to sleep in protected, lead shielded rooms, alone, even if they are married (or they could accidentally kill their spouses).
This is how (human) magic works in Rivers of London books. You have to learn the mental forms in order to do magic, and practice visualising the concepts or it doesn't work. To make things harder, thanks to Isaac Newton, all the names of the forms are in Latin. And the forms have to stack in order to work. To throw a fireball, you have to learn how to visualise the fire, then how to visualise the it moving, then have to visualise how to make it track a target... And after that your brain trickles out your ears (if you've done it wrong).
In Necroscope in order to gain the power to time travel and teleport Harry Keogh, and his heirs, has first to be able to calculate the Infinite length of a Moebius strip in finite terms. When he is stripped of his ability to do math he loses that ability. He has other innate abilities, and most psi users abilities are inborn, but this one has to be learned and expressed mathematically.
The Dresden Files magic stems from life and emotions, but concentration and willpower are what allows one to use magic to achieve anything.
Labyrinths of Echo has an exploration/deconstruction: every single problem with magic is traceable to this - except overtaxing Heart of the World with potentially apocalyptic results (but even this one is aggravated in several ways).
1. Magic is mostly shaped with one's mind, which means the control over magic directly depends on control over one's own mind... the starting level of which, of course, is "jack all", and it takes a lot of exercises to significantly improve. Questionable reliability of non-trivial magic acts under pressure is also yet another good reason to create or acquire "fixed" forms of magic - whether artifacts, stationary enchantments (usually on buildings) or alchemical drugs. As well as for popular support of strict legal limitations on magic, though that still took a century-long civil war.
  - A side effect is that every other random janitor or housewife in Echo can do more than a Great Shaman on another continent, and as likely as not will do something if provoked, but since most people are untrained, they won't even know what they are doing. Thus the Epoch of Codex policy is promotion of well-fed, sleepy complacency and removal of anything that may make people jumpy, at least in the capitol (e.g. ghosts are rarely allowed to stay - by the King's special dispensation, if they have a good reason to hang around and generally avoid scaring people). Conversely, "Forbidden Magic" usually is at the top of the list in the head of anyone who feels a tiny bit rebellious or contrary, and such an attitude in itself is not the safest for magic experimentation. Since the whole mess started because rampant overuse of magic was about to destroy the world, it's a problem. And almost no one really pays attention to this - yet trying to seriously convince people that it was not a political move but a barely dodged catastrophe could lead to freak outs... which is bad for the very same reason. Meaning that even those who know exactly what's going on are trapped in a precarious situation.
  - Also, the common level of control could not be improved: mages could not just train everyone, since training would involve using more magic, and no one would bother to apply without perks, i.e. permit to use more magic still. At least, once the end-of-the-world threat was removed, the new Great Magister dealt with this problem by almost immediately organizing free courses and exams - it's in everyone's interests, after all.
2. Framing magical acts into rituals, spells and/or standard uncomplicated mental constructs is necessary to make them repeatable and reasonably safe - most of the time. A beginner with enough of raw potential still may disintegrate a coffer he tries to unlock or blow up the whole tavern instead of opening one bottle, just because he had an inappropriate mood or visualized something in a wrong way.
3. Of course, the possibility of a magical act by rote creates the next trouble: nothing other than long cautious training or being put into an anti-magic room (which are very rare and used mainly to lock up the dangerous mages and artifacts) prevents those who used a spell once from going through it again, even unconsciously while asleep. Which is fine for babies taught to use grade 2 spell to keep the diaper dry, but becomes obviously unsafe for magic-users throwing fire - and everyone around them, too. For this reason, the last surviving magical Order (and quite likely others before it, as they did survive for long enough to pass the tradition) have the apprentices sleep in cells with as few as possible objects that could be set on fire, animated etc. and little space for other shenanigans.
- This affinity works both ways:
1. Magic is wilful, even if not sapient.
  - Spells tend to "pronounce themselves" once the mage said the first word or two and let enough of power into it. This may help in a desperate situation... But since usually one doesn't know whether there could be a valid spell by changing something halfway in, a spell cannot (or at least should not) be trusted not to pull one's tongue on the wrong track at any moment, thus the mage needs to stay focused anyway. Same deal with creation of magical artifacts - they often push and pull their maker to finish the job, whether it can be done safely or not (for one, late stages of crafting a Death Glove are survivable only with right sort of magical protection, so the inventor and some other people didn't live to see the finished item). This also makes sleep-casting (see above) far more likely to complete, of course.
  - Complex and/or powerful artifacts (and sometimes even "mundane" objects caught in a heavily magicked-up area) may acquire semi-sentience. Normally this means dedication to the intended purpose and sometimes loyalty to the maker/owner. Which either doesn't really matter or makes them somewhat more useful and versatile - at least, for those who can "speak their language", for others it's more of a security problem. Some influences may turn a highly motile trinket violently insane - and/or infect a whole batch of similar enchantments: Utility Magic is common, and demand for goods made slightly better in some way means artisans learn enough of magic to enchant everything they churn out, within limits of their ability and law. Which did happen, for example, in the very first book. Also, for psychometry purpose any magical object is deemed an "untrustworthy witness", as its biases may distort the "testimony".
2. Magic is psychoactive. Rituals boosting magical power are often addictive and/or sanity-disrupting - even before "With Great Power Comes Great Insanity" side kicks in and makes things worse, some paths to power have old good "already too drunk to know when to stop drinking" trap right on the first step. Amusingly, some of them found ways to turn this into an advantage: e.g. users of Holey Chalice normally are less powerful and more sober than during magical exercises - and they managed to avoid accidentally blowing up themselves despite lack of self control training as such. There's also a theory that using power provided by Heart of the World at all gradually drives people crazy... granted, it came from a mage insane even in his own opinion... but also the most powerful one in his generation.
- - Other power sources are not as easy to use and have their own quirks. Good forest mages tend toward "barefoot hippie walking garden" archetype. Invisible Magic is known to almost invariably turn (in the long run) its practitioners into calm, politely smiling, self-aware Cosmic Playthings whose moral compass points somewhere outside visible 3D space half of the time... which generally is good news for other people (they at very least value "existence as such", or literally won't bother to wake up), but while reduction in petty concerns makes them less and less troublesome, by the same token they usually are removed from most worldly affairs by the time they reach "movers and shakers" tier.

Oral Tradition

Most depictions of Merlin fits this. He's a wise advisor, and a powerful wizard.

Tabletop Games

In Dungeons and Dragons, wizards used their intelligence as the stat governing their magic. Clerics used wisdom. In later edition, some classes used charisma. Generally, "Learned" arcane magic was tied to intelligence, divine and natural magic to wisdom, and inborn magic to charisma.
- 4th edition both inverts the trope, and plays it straight. Wizards use intelligence. But classes like the sorcerer and warlock can use physical attributes like constitution and strength to cast magic. Often because the powers they wield are dangerous to themselves, thus they need a fit body to channel them. The Battlemind (a psychic warrior) beats people to death with the power of his physical health (constitution).
In Shadowrun, Magic is it's own attribute, but only the mental attributes (Logic, Intuition and Charisma) can be used to resist drain, the strain of using magic. Thus having higher attributes allows one to cast more spells.
In most Savage Worlds setting, magic is related to the spirit attribute. If not, it's smarts. But always one of those two.
In Magic: The Gathering in-role your cards are your spells, and you draw them from your library. Many cards that affect cards in your hand and library (drawing, discarding, searching, etc.) represent things happening to the mind or knowledge, and a few other cards represent things happening to cards in your graveyard (your discard pile) as affecting memories.
In GURPS, "Magery" (the advantage that allows you to be a mage) is a mental advantage, which means that it stems from your mind rather than from your body (so it stays with you if you switch bodies with someone, etc.)

Video Games

In Ogre Battle, Intelligence determines a magic attack's damage.
In The Elder Scrolls games, Intelligence determines one's mana, thus how many spells they can cast in a short amount of time. Intelligence also governs alot of the magical skills. Those that don't fall under it fall under Willpower or Personality.
- Willpower is also used to determine how quickly your mana regenerates.
In the Ultima games, one's spellcasting depends on either intelligence or wisdom.
In the Wizardry series, spellcasters depend on either intelligence, senses or piety.
Diablo III uses Wisdom as the attribute governing mana and magic damage.
In Warcraft III, intelligence dictates a hero's mana, and magical heroes' damage.
In Final Fantasy IV and Final Fantasy XI, intelligence dictates magic damage. In most other games of the series, Magic Power is it's own stat.
In Quest for Glory, Intelligence affects your ability to cast spells and your mana if you are a Magic User.
In Fable, Magic falls under "Will".
In Dragon Age Origins, Willpower determines mana.
- Interesting subversion in that Cunning—the stat that models the character's raw intellectual capacity, social acumen, cleverness and perceptiveness, does not aid magic in any way.
In the Lufia games, Intelligence determines spellcasting power.
Games based on or inspired by Dungeons and Dragons do this:
- Baldur's Gate I and II and Baldur's Gate: Dark Alliance
- The Neverwinter Nights games
- Temple of Elemental Evil
Golden Sun has this in the form of psynergy, short for psychic energy.
Dark Souls has this with standard sorcery, as intelligence raises your ability to use sorcery catalysts and allows you to learn higher level spells.

Web Comics

Golden Age of Adventurers explains why it's a problem (see the next page).

Real Life

This is the paradigm espoused by the late Isaac Bonewits in his various works on magic, most notably in his first book Real Magic, published in 1972.
- In the 1990s, he quantified this system into generic gaming terms so that it could be incorporated into roleplaying games, resulting in the book Authentic Thaumaturgy, published by Steve Jackson Games.