Magic in Grey Lotus is a freeform system, requiring much effort from the GM to keep abuse to a minimum. It is quite possible to use only the given spells, and forbid players from inventing their own, but the full-fledged system was designed to reward creative players.
At its most basic, ``magic'' is simply the manipulation of the invisible ``ether'' that is always present. A skilled spellcaster first enforces his will on the ether to imbue it with the desired capabilities of the spell, then uses his skill to guide the raw forces into a cohesive effect.
In game terms, this means that a spellcaster must use special ``Focal Skills'' to give the desired attibutes to the spell, ``building'' it from the ground up, and then ``cast'' the spell using his Skill in the required magical Path. This can seem complicated at times, but an experienced player can achieve the desired effect in a few moments.