Think of your most treasured possessions. You might be imagining your new car, or your mobile phone or tablet, your game console, your house, surfboard, bicycle, first edition of Dickens (not bad!), or your model train set. All material possessions – tangible, visible, saleable, heritable, solid and stable, for yours and my admiration. At least that's what our culture encourages you to focus on. But in that case you would forget something far more important.