Let us try and grasp this fact. If we analyse our sense of sight, we find that the only impression made on our bodies by external objects is the image formed upon the retina; we have no cognisance of the separate electro-magnetic rills forming that image, which, reflected from all parts of an object, fall upon the eye at different angles, constituting form, and with different frequencies giving colour to that image; that image is only formed when we turn our eyes in the right direction to allow those rills to enter; and, whereas those rills are incessantly beating on the outside of our sense organ when the eyelid is closed, they can make no impression unless we allow them to enter by raising that shutter. It is not then any volition from within that goes out to seize upon and grasp the truths from Nature, but the phenomena are as it were forcing their way into our consciousness. This is more difficult to realise when the object is near to us, as we are apt to confound it with our sense of touch, which requires us to stretch out our hand to the object, but it is clearer when we take an object far away. In our telescopes we catch the rills of light which started from a star a thousand years ago and the image is still formed on the retina _now_ although those rills are in fact a thousand years old and, invisible to our unaided eye, have been falling upon mankind from the beginning of life on this globe, trying to get an entrance to consciousness. It was, however, only when, by evolution of thought, the knowledge of optics had produced the telescope that it became possible not only for that star to make itself known to us but to declare to us its distance, its size, and conditions of existence, and even the different elemental substances of which it was composed a thousand years ago. Yet, when we now allow its image to form on the retina, our consciousness insists on fixing its attention upon that star as an outside object, refusing to allow that it is only an image inside the eye and making it difficult to realise that that star may have disappeared and had no existence for the past 999 years, although in ordinary parlance we are looking at and seeing it there now.