A geis (pronounced /gɛʃ/; plural geasa, /ˈgɛʃə/) is a dream magic dark in which a person takes upon himself some obligation or restriction in return for special powers granted him so long as he follows its regulations—but risking drastic penalties if he ever breaks them. The adjective geiseach (pronounced /ˈgɛʃək/ or /ˈgɛʃəx/) means "of or pertaining to geasa"; the same word is also used as a noun to refer to a person under a geis, with the plural geiseaigh (pronounced /ˈgɛʃi/). The spelling of this word is often simplified to "geisic", and that of the plural to "geisi" or "geasi", though many scholars still frown upon this heterography.
The conditions of a geis vary widely; they may include abstention from certain foods or activities, or commitments to always partake in certain activities under appropriate circumstances. In general, the more stringent the terms of the geis and the more often and more severely they affect the individual's life, the greater the powers it grants, and the greater the consequences for breaking it. A geis never to eat meat would be more powerful than a geis never to eat raw meat, or never to eat beef; either of those would be powerful than a geis never to eat raw beef. A geis never to speak or write is quite restrictive and places severe limitations on the geiseach and would have commensurately powerful effects; a geis never to say the word "trout" in the presence of a one-eyed woman in a blue hat would so rarely come into play, and its impact on the geiseach's activities would be so minimal if it ever did, that any benefits it conferred would be utterly negligible.
The exact effects of the geis—both the benefits of keeping it, and the penalties for breaking it—vary as much as the conditions, and don't seem to be a priori readily predictable. Usually they affect only the geiseach himself, but they may also affect his environment, his possessions, or even his family or other people and creatures close to him. Some of the effects are truly unusual; there are certain creatures, such as the falseworm, that only exist as a result of broken geasa. Various scholars have postulated means of deducing what advantages a geis will convey that involves a particular restriction or combination of restrictions, but so far, while certain methods of analysis seem to give slightly better results than pure guessing, none has proven really reliable. The same is true of the consequences for breaking geasa, although it seems to be a rule that the repercussions of breaking a geis are always more severe than the benefits for keeping it. For this reason, a geis is something that should only be taken after careful consideration, and only if the geiseach is sure he can abide by its requirements.
Taking on a geis
Taking on a geis requires nothing more than the firm intent to do so. No ritual, incantation, or other formality is necessary. The geiseach's taking on the geis need not be spoken, or communicated to others at all; it is entirely possible to take on a geis completely in secret, with no one ever knowing the geiseach is under the geis. (In fact, some geiseaigh with many enemies may find it advantageous to do just that, lest their foes manipulate them into breaking their geasa somehow.) It is not possible for someone to put another person under a geis; a geis can only be undertaken willingly. There have been many reports of people being placed under geasa by parents or elders, but in reality all the people supposedly "placing" the geis are doing is suggesting that the person take on the geis (though culturally this suggestion may have the force of a commandment). It is only by the person accepting the geis placed on him—and therefore taking it on himself—that the geis becomes valid; should the person have refused the geis, the parents or elders would have had no ability to impose it on him. It is possible to coax or threaten someone into taking on a geis, although verifying that they are really under the geis is difficult. The mere fact that someone says he is taking on a geis does not mean that he is actually doing so—one's words are irrelevant; it is only one's real intent that matters.
There is, however, at least one loophole that sometimes does allow geasa to be imposed on the unwilling. Through thelxis, a person can be made to accept a geis he would not otherwise have been willing to take on; even though he is under magical influence, this may count as being "willing" for the purposes of the geis. However, this is tricky to effect. Not just any sort of thelxis will do; inducing a person to "voluntarily" take on a geis takes considerable power and special arrangements. Spells have been created for just this purpose, though they are rarely used; some mages have found other ways of achieving the necessary thelctic state. In general, however, only very accomplished mages or other powerful beings can force a person to take on a geis against his will, and this seldom occurs.
The fact that a person cannot (usually) be made to take on a geis against his will, however, does not necessarily mean he cannot be affected by it. There are certain geasa that affect the companions and relatives of the geiseach, whether or not those individuals had any say in his taking on the geis—or are even aware of it. Obviously, in such a circumstance, these other individuals, if they know of the geis, may be motivated to help the geiseach follow it. (Geasa that affect the geiseach's possessions may also indirectly affect other people, if those possessions are jointly held or if someone else otherwise has an interest in them.)
Though most geasa are taken on by single individuals, it sometimes happens that entire families, municipalities, or other groups and organizations take on a collective geis. For this to happen, it is not necessary for each person in the organization to individually agree to the geis; the exact criteria for taking on a collective geis depend on the government of the organization, and can be somewhat complex. This is an exception to the rule about people not being able to take on a geis unwillingly; collective geasa can apply even to members of the organization who did not want to take them on (or indeed were completely unaware of them), and can still be in effect generations later when the original geiseaigh are long dead. However, collective geasa usually do not place restrictions and requirements on the activities of individual members of the organization, but rather on the organization as a whole; as long as others are willing to take up the slack and fulfill the requirements of the geis, therefore, it isn't generally necessary for every member of the organization to be involved. Here too there are exceptions, however, and there have been collective geasa that have placed severe constraints on the lives of each person in a town or association.
Breaking a geis
Though the terms of geasa vary widely, each geis does have very definite requirements, the breaking of which immediately brings the geis's consequences upon the breaker's head. With very few exceptions, the breaking of a geis is an all-or-nothing affair; it isn't possible to break a geis in only a minor way and get reduced penalties. Any time a geiseach fails to follow the geis's strictures, the full power of its penalties is invoked.
Even if a violation of the terms of a geis is not intentional, it still counts as breaking the geis. For example, if a man has a geis never to speak to a woman, and then later encounters and greets a woman disguised as a man, the geis is broken—even though the geiseach didn't realize he was speaking to a woman. It's possible for a geis to be broken without the geiseach having any idea why; for instance, if a man takes a geis always to bow in the presence of a noble, and then a noble comes through his bedroom while he is sleeping, then the geis is broken, even if the geiseach never knew a noble was present. For that matter, a geis still counts as broken even if it is physically impossible for the geiseach to keep it. If a man takes upon him a geis always to rub a certain amulet after eating, and then later the amulet is destroyed, then the next time he eats (and doesn't rub the now nonexistent amulet) the geis is broken. For that matter, if a geiseach is so foolish as to take upon themself two mutually contradictory geasa, then when they inevitably fail to fulfill the terms of one in order to comport with the strictures of the other, they are subject to the full consequences of breaking the geasa—even though they had no choice but to break one or the other. This is, of course, all the more reason to be careful with the geasa one takes upon oneself, and to try to be sure not to put oneself in situations when it may not be possible to comply with their terms.
For most geasa, breaking a geis does not mean the geis is thereafter no longer in force. It can be broken repeatedly, incurring more penalties each time—either the same penalties may repeat, or worse penalties may accumulate. This makes taking on a geis impossible to fulfill especially dangerous.
Escaping a geis
A geis is intended as a lifelong commitment, and generally is just that. A few geis do have renunciation conditions, though those that do tend to convey less powerful benefits. Aside from that, no spell or talisman, short of perhaps an eximium, can ever free a geiseach of his burden. However, for a geis of relatively recent origin, there may be ways of escaping—though they are very difficult and rarely employed. There are people known as geiseoiri who have some ability to remove or alter geasa, though they may be difficult to find, and even if they're found it may be difficult to convince them to help. Certain geisini can also free a geiseach from a geis, if fulfilled, though the more stringent the geis the more difficult the necessary geisin.
These methods are only practicable, however, with regard to geasa that are newly undertaken; the longer the geis has been effective, the more difficult it is to escape. Once a geis has been in force for over a decade or so, no mortal magics are up to the task of removing it. Divine magics may be another matter; some gods may have the ability to lift a geis of long standing. However, only the most powerful gods might possibly be capable of this, and even they will certainly be loath to do it. For all practical purposes, once it has been in force for that long, a geis is completely inescapable.
Even traveling to another cosmos doesn't necessarily invalidate a geis. A new geis can perhaps be escaped this way (though intercosmic travel is difficult enough that is certainly isn't an easy way to escape a geis), but once a geis has been effective for long enough, it may actually be able to adapt itself to different arcana, remaining in effect in essentially the same way regardless of the cosmos the geiseach finds himself in. This is not true of all geasa, however, and is in any case a very complicated topic, best treated on a case-by-case basis.
Though the variety of geasa is nearly endless, there are certain conventional categories they are sorted by. There's little meaning to these categories beyond convenience of classification; there seems to be little if any correlation with their effects and penalties.
Behavioral geasa are those that place direct restrictions or requirements on the geiseach's actions. In a sense, all geasa could be considered behavioral; the other categories merely refer to specific types of behavior. Those that are considered behavioral geasa, then, are just those that don't fit into another category. Behavioral geasa, however, often have to do with following a particular virtue, or avoiding a specific vice... at least, according to some moral code. A behavioral geas might, for instance, require the complete abstention from any lying, or from any violence—or more specifically from any violence against women.
Dietary geasa deal with the geiseach's eating habits. Most often, they specify the avoidance of certain foods; geiseaigh commit, for instance, to never eat meat, or to never eat the meat of a specific type of animal. Sometimes dietary geasa avoid the eschewal of specific combinations of food, rather than specific foods, or rather than foods to avoid they may specify foods that the geiseach must eat, either in every meal or at least once every day or in some other interval.
Linguistic geasa place restrictions on the geiseach's speech, most often in the form of certain taboo words he is forbidden from speaking, although they may instead involve taboo phrases or (rarely) sentence structures. Some linguistic geasa don't prohibit any particular words, but involve more esoteric restrictions, such as requiring the geiseach to always speak in rhyme, or to begin all his sentences with the same letter of the alphabet.
An occasional geis is a geis which prescribes a certain action which must be taken under specific circumstances. In some cases, the action must be performed at fixed intervals—once each day, for example, or, more stringently, every day at exactly noon. Holidays are commonly involved in occasional geasa, requiring particular actions to be performed on those days. In other cases, the action must be performed every time particular events occur: every time it rains, for instance, or every time the geiseach sees a rabbit. The action in question may be almost anything, and may or may not be related to the event that triggers it.
Some geasa, known as possessional geasa, place restrictions on the geiseach's possessions. Depending on the geas, "possession" may be defined as actually carrying the object, or as being its legal owner, or both. The geis may forbid the geiseach to own certain objects or classes of object, or, on the contrary, may require the geiseach to have at least one (or some other number) of the object in question. Sometimes the conditions specify proximity rather than real possession; a geis may, for instance, commit the geiseach to never be without a sword in easy reach.
A vestiary geis places restrictions on what the geiseach wears. Like possessional geasa, vestiary geasa may set requirements for the geiseach to always wear certain articles of clothing, or prohibitions against them. Sometimes vestiary geasa place stipulations on their conditions, perhaps requiring, for example, that the articles in question only be worn (or not worn) in public but allowing them to be not worn (or worn) in private.
Creating new geasa
While very easy to do, the creation of a new geis is a rare occurrence because of the danger involved. A person creating a new geis has no way of knowing what it will avail him... or what penalties he will suffer if he breaks it. That the results are so unpredictable is why this is so seldom done; a person taking on a novel geis might find that the benefits it grants him are of no interest to him, due to his particular profession or preferences, and that he has therefore taken on a burden, with dire consequences for laying it down, that grants him no significant advantage. For this reason, most people take upon themselves geasa that are traditional and familiar, that have been used before and have effects that are well known—and they are careful to go strictly by the traditional wording, to avoid accidentally changing the geis's strictures and with them its consequences.
Nevertheless, all those old and tried geasa have to have once been tried for the first time, and even today some rare intrepid souls may choose to take the plunge and take on themselves a geis previously untested. Although little done, this is not at all difficult; the only difference is that while the conditions for an established geis are already set and need not be specified in detail each time, for a new geis the conditions must be set up in detail. To create a geis, one has to carefully delineate the conditions of the geas, as explicitly as possible—the conditions need not be written down, but usually are, the better to keep them clear and well defined—and then resolve the intent to do so, the same as under a well known geis. Once this is done, the geis is taken on, and will be fully in effect... for better or for worse.