Hungry

"Creatures are not born with desires unless satisfaction for those desires exists. A baby feels hunger. Well, there is such a thing as food. A duckling wants to swim, there is such a thing as water. Men feel sexual desire: well, there is such a thing as sex. If I find in myself a desire which no experience in the world can satisfy, the most probable explanation is that I was made for another world."

C.S. Lewis in Mere Christianity

For reading at some point if it is fruitful:
http://www.peterkreeft.com/topics/desire.htm