"Creatures are not born with desires unless satisfaction for those desires exists.=?ISO-8859-1?B?oCA=?=A baby feels hunger: well, there is such a thing as food.=?ISO-8859-1?B?oCA=?=A duckling wants to swim:

well, 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 this world can satisfy,  the most probable explanation is that I was made for another world."
C.S. Lewis