三军可夺气，将军可夺心。

　　是故朝气锐，昼气惰，暮气归。

　　善用兵者，避其锐气，击其惰归，此治气者也。

　　以治待乱，以静待哗，此治心者也。

　　以近待远，以佚待劳，以饱待饥，此治力者也。

　　无邀正正之旗，无击堂堂之阵，此治变者也。

　　这句啥意思：

　　对于敌方三军，可以挫伤其锐气，可使丧失其士气，对于敌方的将帅，可以动摇他的决心，可使其丧失斗志。

　　所以，敌人早朝初至，其气必盛；陈兵至中午，则人力困倦而气亦怠惰；待至日暮，人心思归，其气益衰。

　　善于用兵的人，敌之气锐则避之，趁其士气衰竭时才发起猛攻。这就是正确运用士气的原则。

　　用治理严整的我军来对付军政混乱的敌军，用我镇定平稳的军心来对付军心躁动的敌人。这是掌握并运用军心的方法。

　　以我就近进入战场而待长途奔袭之敌；以我从容稳定对仓促疲劳之敌；以我饱食之师对饥饿之敌。这是懂得并利用治己之力以困敌人之力。

　　不要去迎击旗帜整齐、部伍统一的军队，不要去攻击阵容整肃、士气饱满的军队，这是懂得战场上的随机应变。

　　英文这么说：

　　A whole army may be robbed of its spirit;a commander-in-chief may be robbed of his presence of mind.

　　Now a soldier's spirit is keenest in the morning;by noonday it has begun to flag; and in the evening,his mind is bent only on returning to camp.

　　A clever general, therefore, avoids an army when its spirit is keen, but attacks it when it is sluggish and inclined to return. This is the art of studying moods.

　　Disciplined and calm, to await the appearance of disorder and hubbub amongst the enemy:--this is the art of retaining self-possession.

　　To be near the goal while the enemy is still far from it, to wait at ease while the enemy is toiling and struggling, to be well-fed while the enemy is famished:--this is the art of husbanding one's strength.

　　To refrain from intercepting an enemy whose banners are in perfect order, to refrain from attacking an army drawn up in calm and confident array:--this is the art of studying circumstances.

　　成语故事

　　公元前684年，齐国恃强凌弱攻打鲁国，鲁庄公率军在长勺迎敌，两军相遇，齐军擂起战鼓，鲁军在曹刿的带领下为避其锐气没有擂鼓。齐军第三次擂鼓时士气已经低落，鲁军才第一次擂鼓。鲁军靠的就是一鼓作气的士气以少胜多打败齐军。--《避其锐气，击其惰归》