Equivalent Exchange

This is the law of alchemy that states: to create, something of equal value must be lost. This is the first Law of Equivalent Exchange.

This law can, however, be broken by one using a Philosopher's Stone. Some examples are Zolf's being able to destroy entire city blocks during the Ishval campaign while using the stone and his destructive alchemy.

"Humankind cannot gain anything without first giving something in return. To obtain, something of equal value must be lost. That is alchemy's first law of equivalent exchange. In those days, we really believed that to be the world's one and only truth." -Alphonse Elric