Desire and DNA
Desire is coded in our DNA!
Since the DNA gives us the imperative "Live!", we constantly need to see how to survive. And this incessant process of adjustment, the inherent imperative "Live!" FORCES us to do something, to ACT.
Thus, there is no moment of living being where you have everything fulfilled. Even sleeping is an act. Just relaxing is a necessary act. Everything you do has a meaning within the imperative "Live!". The term "desire" describes the fact that there will always be a gap between the how-it-is and the fact that this how-it-is lacks the property to fulfill every need of us without us doing anything.