This is a 1513 classic copperplate engraving by Albrecht Dürer, called “Knight, Death and the Devil,” also known as “The Rider,” and it represents an allegory on Christian salvation. (Click this link, then on the image itself to get a larger version.)
Unflustered either by Death who is standing in front of him with his hour-glass, or by the Devil behind him, an armoured knight is riding along a narrow defile, accompanied by his loyal hound. This represents the steady route of the faithful, through all of life’s injustice, to God who is symbolized by the castle in the background. The dog symbolizes faith, and the lizard religious zeal.
The lizard is obviously scampering around on the ground looking for someone to evangelize.
Where are the mice? In church, of course, where it’s safe.