Alright, so my substance is simply all that is required to make up that which is me? In that case, how much change can I go through before I am no longer me? How many limbs, body parts, etc, would I have to lose before I can no longer be classified as who I am/was? How do we measure when something has taken on a different substance?
It sounds like this can be applied on a different level. For instance, the human Kidney is made up of cells, so in its own fashion, it is its own substance. Going the other way, You can take a council of bishops. while the bishops are their own substance, but make up the parts for another substance, that is, the council.
But then it seems that this can go on for infinity, or from any reference you want. The bricks of the church, the atoms of the bricks, the particles of the atoms, etc. Is this correct?