"The man who would be a warrior considers it his most basic intention to keep death always in mind, day and night, from the time he first picks up his chopsticks in celebrating his morning meal on New Year's Day to the evening of the last day of the year. When one constantly keeps death in mind, both loyalty and filial piety are realized, myriad evils and disasters are avoided, one is without illness and mishap, and lives out a long life. In addition, even his character is improved. Such are the many benifits of this act. -Daidoji Yuzan, Budoshoshinshu: The Warrior's Primer
If you understand this then do not mourn them but be thankfull that they make the sacrafices of killing and dying."