Physical exhaustion and recklessness in physical habits undermine moral self-control and character.

Original passage

In the battle with disease and death every energy is taxed to the limit of endurance. The reaction from this terrible strain tests the character to the utmost. Then it is that temptation has greatest power. More than men in any other calling, is the physician in need of self-control, purity of spirit, and that faith which takes hold on heaven. For the sake of others and for his own sake, he cannot afford to disregard physical law. Recklessness in physical habits tends to recklessness in morals.