There’s nothing you can do to the number one that changes it. You cannot paint it purple (‡), make it even or get it angry. It’s the number one, it is eternal, implacable and unchanging. Attempting to do something to it – say, adding three to it – doesn’t change the number one at all. Rather, it produces an entirely different and also immutable number. If you cast it to a double, you don’t change the integer one; rather, you get a brand new double.