Aschesis

From the ancient Greek ασκησις, askesis, a trial or test: the act of testing something or trying it out. (The term also has various nonwizardly meanings, mostly involved with the art of philosophy: the word is the distant root of such terms and concepts as "asceticism".)

In wizardry, the act of testing a spell to check whether it has the desired effect. The concept of aschesis does not invalidate the received wisdom that "a spell always works"; it does. But it's smart to make sure the spell in question works the way you intended it to.

Such testing is vital, since a spell, like any other equation, will act differently when its variables are changed -- including such variables as the location in spacetime of the wizard working it, the loci on which the spell is intended to work, etc. There are wizards who spend much or (in some cases) all of their time doing work of this kind ( Tom Swale is one), determining how a spell's results will change under specific circumstances, and what adjustments or conversions have to be done to make it reliably yield the same results regardless of changes in temporospatial location or the other associated variables. Such research wizards' work becomes part of the Wizard's Manual, which uses their data to adjust the spells when making them available to other wizards. (TWD)

(See also aschetic universe.)