Spell points represent the total memorization ability of a wizard
character and memorization is not a thing that happens immediately.
The wizard must have a clear head gained from a restful night's
sleep and then has to spend time studying his spellbooks. The
amount of study time needed is 10 minutes per level of the spell
being memorized. Thus, a 9th-level spell would require 90 minutes
of careful study. Clearly, high-level spellcasters do not lightly
change their memorized spells.
Spells remain memorized until they are cast or wiped from the
character's mind by a spell or magical item. A character who spends
10 spell points to memorize a 3rd-level spell, ties up those points
by holding the spell ready in his memory; the spell points can’t
be used to memorize another spell until the first is expended.
Spell points used to memorize free magicks are also tied up in
the same fashion. A wizard cannot choose to forget a memorized
spell to replace it with another one. He can, however, cast a
spell just to cleanse his mind for another spell. (The wizard
does not get experience for this.) Once a character has cast a
spell, the spell points used to hold that magick in memory are
gone.
