It's the same thing that drives people to want to experience sexual pleasure or have one too many drinks. We all want to experience the other, and to get out of our daily existence.
The earth, that is sufficient, I do not want the constellations any nearer, I know they are very well where they are, I know they suffice for those who belong to them.
But like infection is the petty thought: it creeps and hides, and wants to be nowhere--until the whole body is decayed and withered by the petty infection... Thus spoke Zarathustra.
Let those who want to save the world if you can get to see it clear and as a whole. Then any part you make will represent the whole if it's made truly. The thing to do is work and learn to make it.
How high a price we pay for the burden of habit! I am fitted for life here where I do not want to be, I want to live there but am unfit for it, and on both counts I am miserable.