There was once a bald man who sat down after work on a hot summer's day. A fly came up and kept buzzing about his bald pate, and stinging him from time to time. The man aimed a blow at his little enemy, but his palm came on his head instead. Again the fly tormented him, but this time the man was wiser and said: 
You will only injure yourself if you take notice of despicable enemies. 