Answer:
What is it that you must give before you can keep it.
I work when I play and play when I work.
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
Salty water everywhere but not sea in sight.
Half-way up the hill, I see you at last, lying beneath me with your sounds and sights. A city in the twilight, dim and vast, with smoking roofs, soft bells, and gleaming lights.
You can always find me in the past. I am created in the present, but the future can not change me. What am I?