This here is Terra's Theme, which is also the Overworld music for the first half of the game. It's a combination of flute and piano, and it always feel serene and a little bit haunting to me.

Wanderer of Time is an official remix that includes vocals - translated, they go like so:

Crossing the distant night,
Wandering the desert sea.

The gods' voices are mirages;
The forgotten people.

Shadows flicker palely, then stand;
For one moment, an illusion.

A hero's dream, burning blue,
The people, sleeping forever.