The difference in women is 20 and 40 years. Author's observation.

 A woman in 20 fools, but considers herself smart. And in 40 years the woman is clever, but she considers herself to be a fool. Of course, this is my author's conclusion in no way refers to those women who read these lines. I am sure that you are clever at the age of 20 and 40. I do not even argue. Oh yes, Stas Mikhailov for those women who did not read me.