**Angular 5**

Why does only a variable qualified with an access modifier, in a constructor's signature, get recognized throughout a class?

For eg.

```
constructor(private n: number) { 
} 

fn(){
  this.n = 6; //Allowed
}

```

but

```
constructor(n: number) { 
} 

fn(){
  this.n = 6; //Not allowed
}

```