Little engine that can

I see you chugging along that grassy hill,
along tracks that screech and beg for polish.

I can hear the coals burn and the thunder of your wheels;
can see your strength and courage forged by fire,
cooled into the sturdy iron that builds your frame.

What hill? you say, with a devilish grin.
All you see are tracks, and everyone knows that you own these tracks.