Why is calling a protected or private CSharp method / variable possible? [duplicate]

Question

Possible Duplicate:
Why are private fields private to the type, not the instance?

Consider the following class:

public class Test
{
    protected string name;
    private DateTime dateTime;

    public Test(string name)
    {
        this.name = name;
        this.dateTime = DateTime.Now;
    }

    public Test(Test otherObject)
    {
        this.name = otherObject.name;
        this.dateTime = otherObject.GetDateTime();
    }

    private DateTime GetDateTime()
    {
        return dateTime;
    }

    public override string ToString()
    {
        return name + ":" + dateTime.Ticks.ToString();
    }
}

In my constructor I'm calling private or protected stuff of the otherObject. Why is this possible? I always thought private was really private (implying only the object could call that method / variable) or protected (only accessible by overloads).

Why and when would I have to use a feature like this?

_{Is there some OO-logic / principle that I'm missing?}

Answer 1

From MSDN (C# Reference)

The private keyword is a member access modifier. Private access is the least permissive access level. Private members are accessible only within the body of the class or the struct in which they are declared.

Answer 2

To answer your question:

You can use that for example in a Clone method. Where you need write access to members which may be exposed as read only. Like

class MyClass : ICloneable
{
    public object Clone()
    {
        var clone = (MyClass)MemberwiseClone();
        clone.Value = this.Value; // without the way private works, this would not be possible
        return clone;
    }

    public int Value{ get; private set;}
}