Is a Brave Courageous Man's Heart?

In some accounts it even seems to be seen as a biological reality, either the physiological result of bravery or its cause. So we're talking about a heart that is shriveled, that is cold, that it doesn't have a lot of blood in it and it doesn't quiver. And so for a warrior who's very courageous and very strong in battle, it just happens to be because their heart is this icy little nugget.