That is their nature, what you like today you may not like tomorrow.That is the nature of desire. If desire does not changeit's pointless.What is constantly changes?you buy a new TV, by the time you bring it home, plug it in, turn it on, its advertising a new TV and you will desire you that.You will go to a restaurant, you will look at the menu and after careful deliberation, you will order your dishand when your dish arrives you will look at your neighbor