PROVE ALL THINGS
In the abstract anything can be, may be, but when merged with reality, anything that is abstract transmutes within defining limits.
Otherwise stated, abstract theory succumbs to what is practicable.
Thus, courage is defined both by the circumstances all around and within its bearer; so too is virtue.
This may be why the Bible says:
"Prove all things; hold fast to that which is good." 1 Thess 5:21