Full Document Text Size Change

[Nels Drue Daily]

Hello LilyPond Users!
I recently posted a request about how to change the size of all text 
within a document without changing the staff size. I'm wanting to
use a different font that is naturally smaller than the default Century 
Schoolbook.
Someone responded this way:

"I set the text-font-defaults in the paper block to an alist 
containing the font-size, baseline-skip and word-space properties.
Then I set in the layout block the font-size to 0 for MetronomeMark, 
RehearsalMark, BreathingSign, StanzaNumber, LyricText and many 
other grobs that would otherwise adhere to the global font-size."

I would like to try this, but would like an example of the coding 
needed to make it happen. Can anyone help me? Thanks!