The need for sex and food are animal desires, because animals have them as well. Even being in full isolation man feels hunger and the urge to reproduce, i.e. to have sexual relations. Desires for wealth, power, fame and knowledge are already human desires, since to satisfy them man must be surrounded by other people.
If we examine the pleasure we derive from having knowledge, domination, honor, wealth, or pleasure from food or sex, it seems that in all these cases, the greatest pleasure is experienced in the brief encounter between the desire and its satisfaction. From the moment we begin to fulfill our desires, the pleasure diminishes. Pleasure from satisfying a desire may last minutes, hours or days, but it does fade. Even if we spend many years trying to obtain something, like a prestigious office, once we have it, we lose the sensation of pleasure.