Here's why:
* Proper nouns are specific: "Edward" refers to a particular individual.
* Common nouns are general: You can't use "Edward" to mean "any person" or "a person in general."
Here are some examples of how you *can* use "Edward":
* As a name: "Edward is my friend."
* In a possessive form: "Edward's car is red."
* As part of a title: "King Edward"
Let me know if you have another question about nouns or language!