A much larger work. Whether that work shall appear will depend on the reception met with by the present tract There is but one thought here set forth, and that thought is, that the medium of seeing is elementally correlated to the media or objects of the other senses in other words, that all forms of matter are derived from the same stock of elements. That is the proposition sought to be proved. It is virtually proposed by Newton in one of the questions at the end of his Optics and that the reader may be the more disposed cautiously to estimate the proof it rests upon, he may be here informed that its chief and most startling consequence, if true, is, that the creation and constant enlargement of our globe and its planetary kindred is the very work which.