The Pattern of Amber
A key item in the universe described by Roger Zelazny's Amber series. The following description is written as though by someone who lives within Zelazny's fictional universe.
It is a matter of some debate whether the Pattern represents, creates, reinforces, or defines order (as opposed to chaos, for which the Logrus embodies the same debate). This uncertainty is due, at least in part, to the practical rather than theoretical approach to life taken by the majority of Amber's royal family. (This indifference by most of Oberon's children is much of the reason Brand could so easily precipitate and almost win the Patternfall War). It is known that the Pattern is strongly linked with the Unicorn, which is by no coincidence the foremost symbol of both Amber and Oberon's family. In any event, though its origins and existential foundations are not fully understood, many of the Pattern's effects, capabilities, limitations, and properties are well-known.
Known History of the Pattern
The exact circumstances of the Pattern's creation are somewhat hazy: its creator (which term may not be entirely accurate), Dworkin, was made insane by the damage done to the Pattern as the opening gambit of the Patternfall War. Prior to those events, most children of Oberon chose not to pursue the existence of the Pattern any further than necessary to make utilize various of its special properties. In retrospect, it seems likely that Oberon knew more about the Pattern than anyone save Dworkin, and Brand's knowledge of its workings was only surpassed by Oberon's. Neither, however, was terribly forthcoming in this regard prior to his death.
It is known that Dworkin himself was born (if that term applies) in the Courts of Chaos. In some fashion, he arranged to make off with the Jewel of Judgement, which gem contains a three-dimensional version of the Pattern. This "higher" Pattern may or may not be the fundamental Pattern, but it is the parent of the Pattern of Amber. "Where" Dworkin created the Pattern (or was used by the Pattern to create itself) is a question without meaning: the act of creating the Pattern defined the place later known as Amber; an opposition to Chaos. In the instant of the Pattern's creation, the Shadows were created, occupying and defining the continuum between Amber and the Courts.
In terms of technique, Dworkin presumably created the Pattern by focussing his will through the Jewel of Judgement and physically walking a line which described the Pattern. How he settled on the path of this line is not precisely known; it is a reasonable assumption to think that he was "inspired" by the higher-order Pattern of the Jewel, and the Pattern he walked was his best two-dimensional approximation thereof. The only evidence of this, however, is Corwin's later efforts to recreate the Pattern near the end of the Patternfall War. The difference, of course, is that Corwin was consciously attempting to create a Pattern identical to Amber's, whereas Dworkin was working with a tabula rasa, as it were.
The Pattern of Amber, though commonly thought to be the Primal Pattern, is not. The Pattern to be found beneath the palace in Amber is simply the first Shadow of the true Primal Pattern. The true Pattern resides on the same geographical spot, but on a slightly higher plane of existence, the achieving of which is a non-trivial exercise, though easily accomplished by Oberon, Dworkin (at least when he is control of all his faculties), and Brand. It is certainly possible there are others who can arrive there at will, and it is virtually certain that anyone capable of traversing shadow can learn how.
Properties of the Pattern
The foremost property of the Pattern is its shadowcasting: its existence defines a reality opposed to that defined by the Logrus. Between these two poles exist Shadows, distorted reflections of Amber and the Courts of Chaos. A Shadow's degree of resemblance to one or the other depends on (or, possibly, defines) its "proximity" to the primary.
Along with casting Shadows, Pattern Initiates (those who have traversed the Pattern) are granted the ability to walk amongst Shadows. Something of a complement to this granted power occurs once one has successfully walked the Pattern: while at its center, one can command the Pattern to send one to virtually any location. It is important to bear in mind that the Pattern is a manifestation or representation of a higher consciousness; a vague or poorly-worded destination is open to the Pattern's interpretation, with sometimes unpredictable results. Also of some note is that, technically, walking the Pattern is not required to use this ability. If one somehow arrives at the center of the Pattern without actually following its curves, one can still use its transportation. There is reason to believe this ability is independent of one's relationship to the Pattern's creator/parent/tool, Dworkin (i.e., this is possible even for one not of Amber's blood).
While the Pattern controls and grants access to vast powers, it is hardly impervious or omnipotent. Though the reasons are uncertain, it is known that the blood of Amber is anathematic to the Pattern: one small drop can destroy an inch or two of the Pattern; larger quantities can do proportionately more damage. This, of course, is what (arguably) started the Patternfall War: Brand knifed Martin, Random's estranged son, at the location of the Primal Pattern, spilling a large quantity of Amberite blood, and cutting a swath of destruction all the way from the Pattern's outer edge to its center.
This destruction serves to demonstrate another property of the Pattern: its universal nature. Since the Pattern is what defines, in part, every Shadow, the destruction was reflected in every Shadow between Amber and the Courts. Though its physical manifestation in various Shadows varied, it served as a continuous path from the Courts to Amber through Shadow, along which an invasion could move. Interestingly, though the Pattern's damage was reflected in every Shadow, it was not reflected in every Pattern in Shadow. Most notably, the Pattern in Amber did not appear damaged. Rather, the destruction evidenced itself as a black road running towards the city through the Forest of Arden.
Perhaps this lack of damage in the reflection should be less than surprising, however, given that reflections of the Pattern do differ from the Pattern itself; those differences being of greater and greater magnitude the further from Amber one travels in Shadow. These reflected Patterns quickly become useless to a true Amberite, as they contain breaks in the line. However, for someone who is not of the blood of Amber, they can serve as another path to power. It is a dangerous undertaking, but one can maneuver through the breaks in the line towards the center of some reflections, and gain mastery of a pseudo-Pattern magic. This power is inherently more dangerous than true Pattern magic, and, though spectacular, is unlikely to best Pattern (or Logrus, for that matter) magic in an even contest.
Though much is known about the Pattern's how, far too little is known about the Pattern's why. Some hints can be picked up from the interaction between the Pattern and the Logrus, as well as the interactions of both with Merlin's Ghostwheel. Both of those entities, however, are highly subjective in their perceptions of the universe and each other. Hence, they make less than ideal sources of information. The mortality rate amongst those loyal to Amber who may have more information has been unfortunately high. Meanwhile, though much knowledge is certainly contained within the Courts, the residents there have no interest in disseminating it. The recent turmoil, and Merlin's resulting position may help to alleviate this problem; this, of course, remains to be seen.