Which one of us exercises on the old treadmill?

Puff warm breath on your tiny hands.
You wish you were a man
who every day can turn another page.
Behind your glass you sit and look
at my ever-open book ---
One brown mouse sitting in a cage.

Do you wonder if I really care for you
Am I just the company you keep
Which one of us exercises on the old treadmill
Who hides his head, pretending to sleep?

- One Brown Mouse, Jethro Tull