First Law

   All that lives must die.

The first law, written into the code of the Great Mechanism after the Dawn War is that of the inevitability of death. And beyond that, the connection between growth and death is assured:

   Those that cannot die, cannot live. Life is growth. Without the possibility of death, there is no growth.

This means that those who seek to avoid death and avoid risks grow slower, if at all. Immortal beings such as gods, demons, angels, and elementals hardly grow at all. Choosing to become undead (especially via lichdom or vampirism) stunts your growth. This also explains why adventurers, who risk everything continuously, grow so much faster...if they survive.