Magic requires the magic user to speak words of power from the language of creation, and use their soul's energy to give the word power. These words of power allow the magic user to impose his will upon and command reality, temporarily bending or disregarding the laws of physics to cause an effect in accordance with the word of power spoken, or a "spell" in layman's terms. By speaking several words of power, the effect is changed in accordance to those words of power. A magic user's state of mind, grammar, pronunciation, and accent all influence the spell's result.
For example, Bob the Wizard wants to cast a fire ball spell, so Bob speaks in the language of creation, "FIRE-BALL-THROW", depending on Bob's discipline, enunciation, and intent, the spell could fizzle out, summon and throw a fire ball, summon and throw dozens of fire balls, summon and throw one enormous fire ball, or light Bob on fire. When casting a spell, the magic user must use his soul as fuel for the language of creation, to give the words the power to command reality.
The soul is layered, made up of the consciousness, memories, personality, emotions, and thoughts of the magic user, in that order. When a magic user casts a spell, their mind essentially dissolves a part of itself to power the spell. At first, the magic user only loses the thought that went into the spell, but if they continue, they'll begin to lose their emotions, personality, memories, and eventually, consciousness, suffering total oblivion.
The loss of a magic user's thoughts and emotions can be easily replenished with enough rest and meditation, but damage to their personality, memories, and consciousness is either permanent, or requires a herculean effort to repair.
Wizards are those who learned some of the words of the language of creation and how to channel them in spells themselves. Sorcerers are those who made a pact with a supernatural entity, allowing it to graft a part of its soul onto the Sorceror's, giving them highly specific magical powers with no need of knowledge or technique to apply, in exchange for the Sorceror's soul upon death, lifelong mortal servitude, or the completion of a favor of some kind.