Plutarch 
Plutarch’s Lives. Book II 

Cato the elder, speaking to some persons who were praising a man of reckless daring and audacity in war, observed that there is a difference between a man’s setting a high value on courage, and setting a low value on his own life—and rightly. For a daring soldier in the army of Antigonus, but of broken and ill health, being asked by the king the reason of his paleness, confessed that he was suffering from some secret disorder. When then the king, anxious for him, charged his physicians to use the greatest care in their treatment, if a cure were possible, at length this brave fellow, being restored to health, was no longer fond of peril and furious in battle, so that Antigonus reproved him, and expressed surprise at the change. The man made no secret of his reason, but answered: ‘My, king, you have made me less warlike by freeing me from those miseries on account of which I used to hold my life cheap.’ And the Sybarite seems to have spoken to the same effect about the Spartans, when he said that ‘they do no great thing by dying in the wars in order to escape from such labours and such a mode of life as theirs.’