Updated: Jul 7
A person is called a "small Universe" because it is possible for man to have the Universe within one's mind and become the Universe.
While a person's body is a "small Universe" that resembles earth, a person him/herself is not just a 'small Universe' but the Universe itself. It is said that all creations exist just as they are inside a person but this is only one's point of view. When a person dies after having been born in the Universe, one returns to the Universe; likewise, the Universe exists, just as it is, in oneself. It is not one's thoughts that allow the Universe to exist. A person is not a 'small Universe' but one is the Universe itself just as it is. The person's mind is the Universe.