What is the reason behind “non-static method cannot be referenced from a static context”?

Question

The very common beginner mistake is when you try to use a class property "statically" without making an instance of that class. It leaves you with the mentioned error message:

You can either make the non-static method static or make an instance of that class to use its properties.

Why? I am not asking for solutions. I would be grateful to know what is the reason behind it. The very core reason!

private java.util.List<String> someMethod(){

    /* Some Code */

    return someList;            

}

public static void main(String[] strArgs){          

     // The following statement causes the error. You know why..

    java.util.List<String> someList = someMethod();         

}

Answer 1

You can't call something that doesn't subsist. Since you haven't designed an object, the non-static method doesn't exist yet. A static method (by definition) always exists.