A friend recently introduced me to a lovely pair of German antonyms - Heimweh (homesickness) and Fernweh (faraway sickness). The latter word doesn't have an exact parallel in English. The closest word is probably wanderlust. In traditional American music, one afflicted with fernweh would be called a rambler.
A man gives an injunction to his lover in the blues song Leavin': "Don't let my leavin' grieve you. When it comes to rambling, lord, I'm natural born." This other side of leaving, of wandering - the pain of loved ones left behind - is portrayed nicely in the Odyssey. Euryclia bemoans Telamachus' decision to travel to Pylos and Sparta, crying "Why, dear child, what craziness got into your head? / Why bent on rambling over the earth? / ...Don't go roaming over the barren salt sea / no need to suffer so (2.401-409)!"
In the Epic of Gilgamesh, Gilgamesh's mother offers similar sentiments in her prayer to the godess Shamash: "Why have you imposed--nay, inflicted!--a restless heart on / my son, Gilgamesh! / Now you have touched him so that he wants to travel (3.45-48)..."
Fernweh is portrayed in both epics as a curse, a cause of suffering . Perhaps it is, but no use telling that to the traveler. And perhaps fermweh isn't so antonyminous to heimweh. Perhaps fernweh/wanderlust is a type of home sickness - a longing for a yet undiscovered home.
Horace asks his friend Grosphus "Why do we aim at so much in our short years? / Why trade our home for lands warmed / by other suns? No one can expatriate himself from himself (Odes, 2.16)." We may know better. But we long. And we try.