"For a traveler going from any place toward the north, that pole of the daily rotation gradually climbs higher, while the opposite pole drops down an equal amount"

This quote by Nicolaus Copernicus is describing the Earth's rotation around its axis. As a tourist moves north, the pole of the daily rotation (the North Pole) will gradually increase greater in the sky, while the opposite pole (the South Pole) will drop down an equivalent quantity. This is due to the Earth's rotation, which causes the North Pole to appear to move in a circular motion around the sky. This phenomenon is referred to as the diurnal motion of the stars. The diurnal motion of the stars is triggered by the Earth's rotation, which triggers the stars to appear to relocate a circular movement around the sky. This is why the North Pole appears to move higher in the sky as a tourist moves north. This quote by Nicolaus Copernicus is a reminder of the Earth's rotation and its result on the stars.