In the real world, our memories fades with time, and two people may remember the same event somewhat differently. In Eidolons, both people may be correct. Perhaps you and your brother were attacked by the neighbor's dog as children. In your memory, you were bitten on the leg—but your brother also remembers being bitten. You both have the scar to prove it, so who is correct?

Such discrepancies are ubiquitous, and as culturally accepted as the inevitability of old age in real life (whereas in Eidolons, ironically, old age is avoidable). While a few historians struggle in vain to map out the past in all its fickleness, many cultures actually welcome this freedom from objective history. In particular, the mystic nomads (see below), who revere chaos, embrace this phenomenon, calling it "flow." The technomagical prophets, on the other hand, refer to it as "entropy," and the Durus Empire calls it "the blight."

There are specific events that comprise the flow. You feel a rising sense of vertigo, until your mind rings like a gong, and reality shifts around you. When you regain your bearings, people and places may appear differently. The discrepancies may be as trivial as the color or style of armor worn by a comrade, or as significant as his entire appearance, gender or skills. Occasionally, a person is gone, and even more rarely, two twins stand where before there was but one. The nomads refer to such an event as a "surge," while the technomagical prophets call it a "quake." The martial ideologues refer to it as a "disturbance."

What doesn't change:

• Physical or natural laws of the world, such as gravity.
• Major geographical features such as the location of mountains, seas, ley lines and nexuses.
• Anything within the empire of the ideologues.
• The Temple of Sigil.

How often do events occur?

Quakes occur "occasionally." We have intentionally not been more explicit than that. Some areas may have quakes being more common than others. But there are unlikely to be more than several minor quakes per day, and not less often than one every few weeks.

Think of it like a gaussian probability function. Most quakes are minor, with minor changes. Occasionally one might fall outside two standard deviations and have more major ramifications. But really outrageous things are simply infinitesimally unlikely to occur, like all the molecules in your body simultaneously tunneling a mile away.