Zinc and Brass: Comparing Allomancy and Feruchemy

[Isomere]

I have been trying to make correlations between Allomancy and Feruchemy. It seems every type of feruchemical ability can be burned by Allomancy, then compounded. This makes me think the magic associated with a given metal is based on the same fundamental source power. Some Allomantic abilities, such as the external mental powers, don't seem to correlate to the feruchemical powers of the same metal. 

 

Allomancy:

• Zinc: Heats up emotions
• Brass: Cools down emotions

Feruchemy:

• Zinc: Mental Speed
• Brass: Warmth

Physical warmth is simply a measure of how fast each particle of a substance is moving. But why would physical warmth be related to cooling down emotions? If you want to heat something up, you need to add energy to the system. I propose the energy for this comes from the cognitive realm.

 

Lets look at the other two: mental speed would mean that the cognitive realm has increased energy to perform it's tasks. If this theory is correct, that energy would come from the physical realm, and would leave an area a bit colder than before. 

 

Theory: External Mental powers transfer energy between the physical and cognitive realms. 

[Phantom Monstrosity]

They don't correlate with each other. They originally did in a rough draft, then Sanderson looked back at "The Final Empire" after it was published and was like "Oh schnapp, I just listed warmth as a feruchemical power matching to a mental metal! I've swapped its effect with determination!", so the entire thing's been revised and allomancy, feruchemy, and hemalurgy now work under different systems from each other.

[Voidus]

The energy for feruchemy comes from storing it in the first place, if it comes from another realm it completely unbalances the system.

[Isomere]

Yup, looks like I was trying to read too much into this. I found this quote: 

 

Q: How is heat a mental attribute in Feruchemy?

A: Because I messed up. I don't know if I've mentioned this before, but that power was supposed to be swapped with another one. (You might be able to guess which one.) However, by the time I realized my mistake, it had already been canonized in print in the trilogy, so I was stuck with it. I've been tempted to go back and correct the error, but it reaches pretty far back. People drawing upon warmth is mentioned in the first book. One thing to keep in mind, however, is that in general the 'physical, mental, etc' things are applied by people--they are boxes that people investigating the magic have used to describe it.

 

 

It looks like there is SUPPOSED to be a correlation between the Feruchemical and Allomantic metals, but this one is an anomaly

 

[Phantom Monstrosity]

There's another quote that says feruchemy is grouped into eight physical, four cognitive, and four spiritual.

[Windrunner he/him]

I'm fairly certain that quote was from before Brandon discovered the error.