Brave from ignorance and folly

I read a sentence:

It is not fortitude to be brave from ignorance and folly.

Why we use from in the construction brave from?

What is the full meaning of the sentence?

It means "...to be brave because you are ignorant and foolish".

A person who goes into a dangerous situation even though they are fully aware of the risks is more truly brave than one who rushes in without stopping to think.

I don't think from should be used here, rather out of.

Here is an example in an article heading: Objective knowledge out of ignorance: Popper on body, mind, and the third world

Another one: Probability magic or knowledge out of ignorance