Discretion is the better part of valour

What's the meaning of the phrase 'Discretion is the better part of valour'?

Literal meaning.

What's the origin of the phrase 'Discretion is the better part of valour'?

Shakespeare, in Henry IV, Part One, 1596:

Falstaff: 'The better part of valour is discretion; in the which better part I have saved my life.'

See other - phrases and sayings from Shakespeare.