"The only proof capable of being given that an object is visible, is that people actually see it. The only proof that a sound is audible, is that people hear it: and so of the other sources of our experience. In like manner, I apprehend, the sole evidence it is possible to produce that anything is desirable, is that people do actually desire it. If the end which the utilitarian doctrine proposes to itself were not, in theory and in practice, acknowledged to be an end, nothing could ever convince any person that it was so. No reason can be given why the general happiness is desirable, except that each person, so far as he believes it to be attainable, desires his own happiness."
- John Stuart Mill (Utilitarianism, 1863)
Mill suggests that happiness is an end to all desire. Anything which we desire is only an answer to our search for ultimate happiness. He also suggests that we do not necessarily need to meet our desires to be happy; that happiness can be found simply through the thought of our desires.
I do not need to own the car I desire. I can be happy just by thinking about the car, by focusing on my desire and meditating on my future happiness.