Page:The wonders of optics (1869).djvu/35

Rh to procure exact representations of natural scenery; but in making inquiries into the subject, he found that his juvenile observations had been made a little too late, photography having already gained the end he intended striving for.



Seeing that the images of all objects appear on our retina upside down, the student is naturally disposed to ask how it happens that we do not see them in that position. Physiologists and natural philosophers have advanced numerous theories on the subject. Some, with Buffon, admit at once that it is by habit and education of the eye that we see objects unreversed. Others, like the great physiologist Müller, imagine that as we see everything upside down, and not a single object only, we have no points of comparison, and practically ignore the reversal. The truth, however, appears to be that it is the brain, and not the eye, that possesses the power of determining the real position of what we see. That the eye alone has no power of determining the positions of objects by itself, may be easily proved by showing a person an astronomical object, such as the moon through a telescope. Unless the observer has