There is a limit, across which man cannot carry any one of his perceptions, and from the ulterior of which he cannot gather a single observation to guide or to inform him. While he keeps by the objects which are near, he can get the knowledge of them conveyed to his mind through the ministry of several of the senses. He can feel a substance that is within reach of his hand. He can smell a flower that is presented to him. He can taste the food that is before him. He can hear a sound of certain pitch and intensity; and, so much does this sense of hearing widen his intercourse with external nature, that, from the distance of miles, it can bring him in an occasional intimation.

But of all the tracks of conveyance which God has been pleased to open up between the mind of man, and the theatre by which he is surrounded, there is none by which he so multiplies his acquaintance with the rich and the varied creation on every side of him, than by the organ of the eye. It is this which gives to man his loftiest command over the scenery of nature. It is this by which so broad a range of observation is submitted to him.