You aren't. If you have a non-const node, you can access its children non-constly _or_ constly (which you could do anyway, since you could make your reference

You aren't. If you have a non-const node, you can access its children non-constly _or_ constly (which you could do anyway, since you could make your reference to the node be const at any time). If you have a const node, you can only access its children constly. This makes perfect sense.