Yes,thats true.
For your body to be the battery..spells would cost HP.
And wizards would hate that.(A system like the Starwars RPG would be neat,where they have Vitality Points and Hit Points..I could see mana being used like the Force)
In any case,wizards should work like sorcerers in 3rd..having to memorize what spells you are going to cast that day sucks.(Who knows if Fireball or Grease is going to be needed?)
I dunno,just felt like ranting for the wizzies ( even though i never play one
)