And that allows us to focus our image onto our retina at the back of our eyes. So remember, from physics, we should know that because the lens is a convex lens, that basically creates a real image found on the back of the eye on the retina. And that image is upside down, it's inverted. So actually, when the image is taken to the brain, the brain actually has to flip that image right side up. And that's exactly why we see things the right way up, the right side up. Now, let's discuss our retina.