Relativity

Einstein was invited to a ceremony held by one of the ladies. During the ceremony, one of them asked him to explain the theory of relativity, and told the following story:
I walked once with a blind man, I reminded him that I love milk, he asked me: What is milk?
I said: It is a white liquid.
He said: I know what is liquid, but what color is white?
I said: It's the color of swan feathers.
He said: The feathers I know, but what is the swans?
I said: It's a twisted bird.
He said: The neck I know, but what is the meaning of twisted?
Then I took his arm and extended it, then bend it, and I said to him: This is the meaning of twisting, convinced, and said: Now I know what is milk !!
Then I turned to the lady and said, "You still want to know what is relativity theory?"