The Gift
Some people in Mythic Europe are blessed with the Gift of Magic. Aligned with the Magical Realm of power, these people are capable of wielding magic. If left untrained, their magical aptitude will usually manifest in idiosyncratic ways, in a specific Supernatural Ability and Virtues reflective of their nature and circumstances. If properly trained, a Gifted child can learn to master the Hermetic Arts and be inititated into the secrets of Hermetic magic. Magi are often very keen on locating promising Gifted children, to be raised as apprentices.
A French version of this page is available: Don
Social Effects
The Gift is unnatural, and repulsive to mundanes and animals. This makes it difficult for magi and other Gifted people to have normal relationships with people. The so-called Gift is a mixed blessing, and the term itself is tinged with irony.
Some characters are blessed with the Gentle Gift, or with a Gift amicable to certain kinds of creatures (see HoHMC). Others have a Blatant Gift, or a Gift particularly intolerable to certain beings (see HoHMC again).
Social Effects in Fifth Edition
The social effects of the Gift have definitely changed from Fourth Edition to Fifth - In Fourth Edition, the Gift provided a penalty to social rolls with mundane beasts and people. (ArM 4 p. 17. p. 35 describes the penalty with regard to normal people and animals for the blatant gift). In Fifth Edition, the social affects of the Gift apply to other supernatural beings as well, including other magi, unless such a being or its race specifically isn't affected by the Gift. Magi in Fifth Edition are able to interact with each other because the Parma Magica now blocks the unease and distrust engendered by the Gift.
The social effects of the Gift are explained on pages 75-77 of ArM5. A lot more text is devoted to explaining the Gift than has been done in past editions, and the description of the social effects of the Gift is harsh and unequivocal: Far from simply giving a penalty to social interactions, this ensures a bad reaction from the start, against which you've got to struggle all the way through. This has led many veteran players, who had interpreted the Gift's effects more moderately, to regard the rules as changed (and these players generally think the change is for the worse). Other people say the description of the Gift in Fifth Edition matches the way they've always played it, and that it helps ensure the importance of both companions and the Gentle Gift.
So, the extend of the difference depends on how you played the Gift before Fifth Edition came out. If you think the effects of the Gift have changed for the worse, don't feel forced into a different interpretation just because a new edition came out. You can always overrule the book (see Robbie's Mantra).
What Causes the Gift
The origins of the Gift are mysterious and unclear. While it can potentially be obtained in the Garden of Eden, it can also be gained by one who undergoes Odin's Sacrifice, meaning it may not necessarily be a Divine gift. Additionally both the Faerie and Infernal powers can replicate the effects of the Gift including magical ability.Its provenance and nature remain unknown. There are rumours that Cult of Mercury used to be able invest initiates with the Gift but that was lost long before Order was founded.
Opinion & Commentary
Why The Gift Has Social Effects
I infer that the designers created the social effects of the Gift to keep magi separate from the society of Mythic Europe. The setting Ars Magica aims for is a plausibly medieval society with fantasy elements woven tightly in. It is not aiming for a fantasy setting where wizards have replaced the entire noble class. If normal people don't trust magi and wouldn't accept their rule, that offers one post facto explanation why Mythic Europe looks the way it does. (Lords of Men spends a few pages discussing several well-thought-out alternative explanations why magi don't rule Mythic Europe.) The social effects of the Gift also create a need and an opportunity for non-magus characters to act as intermediaries between magi and the rest of society. Companions can serve this purpose very well, and grogs -- especially grogs with social skills -- can be an alternative. (Grogs without social skills, attempting to act as intermediaries between magi and mundanes, is a running joke in my Saga that somehow never gets old. I encourage you to try it!)
References
The edit history of this page before August 6, 2010 is archived at Legacy:the_gift.