Can you acquire courage?

The long-running series in which readers answer other readers’ questions on subjects ranging from trivial flights of fancy to profound scientific and philosophical concepts• This week’s replies: why does a song sometimes get stuck in our heads – and what makes an earworm?Is it possible to acquire courage if you don’t have it? I was moved this week by the story of the Australian boy who swam to land for several hours in rough seas to raise the alarm that his mother an