When we are on the path of knowledge, how do we define the limits of fulfillment?
Wherever the mind can go, that is its jurisdiction. When a desire gets fulfilled, the mind goes away from it.
For example, if you want an umbrella, that is the area of desire. Once you get the umbrella, why would you think about the umbrella? Till you get the umbrella, the mind looks for it. Once you get what you desire, the mind moves away from it. This is a natural tendency of the mind. The mind thus keeps wandering from one desire to another.
In the path of knowledge, whatever is needed for us will come by itself.