"No war. Stop the war. Don't believe the propaganda. They are lying to you here." These are the words that Russian journalist Marina Ovsyannikova scrawled on a large piece of paper before she burst on to the backdrop of Russia's biggest news programme.

She only managed to stay on the air for a few seconds, but her act of staggering courage has sparked a discussion of what it means to be brave.

This is a subject that has fascinated us for thousands of years. One of the first to write about it was Laozi, founder of Daoism. He suggested that courage is derived from love, and the greater one's love, the greater one's courage.

Ancient Greek philosopher Aristotle thought courage is a happy medium between cowardice and recklessness, which should both be avoided.

Likewise, Scottish thinker David Hume suggested great courage is necessary to turn a person into a hero, but too much leads people to seek out unnecessary dangers, and in doing so ruin their own lives.

But it might be that you cannot help whether or not you are brave. Scientists now believe that we are hard-wired to be either brave or cowardly.

When we are threatened, the brain has to choose between four responses to the threat: fighting, running away, freezing or collapsing.

Each one of these responses had advantages for our ancient ancestors. If we are able to fight off the threat, we might want to do that. If we are not, it is preferable to run away. If we cannot outrun it, then we should play dead - many large predators do not eat things that are already dead.

But not all our brains pick the same option. Sometimes there is an evolutionary advantage in choosing bravery, and sometimes the coward is more likely to survive. The species as a whole benefits if some are brave and others are cowardly.

Yes: Madness means acting in a way that is not conducive to our own self-preservation. Courage often leads us to take needless risks, and can sometimes put our loved ones in danger as well.

No: True courage is different from recklessness, which drives a person to seek out risks for their own sake. It means bearing adversity with fortitude and standing up for what is right.

Or... Perhaps bravery is a little bit mad, but then cowardice can drive us insane as well. It could be that madness is simply part of the human condition.