It means a strong desire to live taking the form of a readiness to die.

"He that will lose his life, the same shall save it," is not a piece of mysticism for saints and heroes.

It is a piece of everyday advice for sailors or mountaineers.

It might be printed in an Alpine guide or a drill book.
This paradox is the whole principle of courage; even of quite earthly or quite brutal courage.

A man cut off by the sea may save his life if he will risk it on the precipice.