One day, the father lets eight year-old son send a letter, the son took the letter , the father then remembered didn't write the address and addressee's name on the envelope.
After the son comes back, the father asks him: "You have thrown the letter in the mail box?"
"You have not seen on the envelope not to write the address and the addressee name?"
"I certainly saw nothing written on the envelope."
"Then why you didn't take it back?"
"I also thought that you do not write the address and the addressee, is for does not want to let me know that you do send the letter to who!"