His work being finished, he left Leipsic for Cassel, and passing homewards through Gotha, Brunswick, and Hamburg, arrived at Stockholm in July, 1734. It is to be remembered that in this journey he had still the duties of his office in view. He visited mines everywhere, studied their modes of working, and sought continually to make himself useful to his country. It now becomes necessary to speak of his great volumes of philosophical and mineral works. CHAPTER IV. _Opera Philosophica et Mineralia._ In attempting to give the reader an idea of the contents and aims of this great work, within the compass of a few paragraphs, one feels extreme difficulty in knowing where or how to begin. It starts so many topics, is so full of the deepest scientific truth, speculates so boldly, and reaches to such heights of subtle thought, that we must necessarily confine ourselves to a very superficial view, and the enumeration of a few of its prominent features. As before said, the work occupies three large folio volumes. Of the second and third of these, it does not lie in our province to say much. Both are strictly practical works; one on iron, and the other on copper and brass. They are evidences of Swedenborg’s ardent devotion to the duties of his office; and as a testimony to the worth of the books themselves, it need only be said, that portions of them have been repeatedly reprinted, and that they are held in high estimation by those who study metallurgy as a science, or follow it as a profession. The publication of the secrets of trade and manufacture in these volumes, was not relished by the narrow-minded and selfish. Of such the author observes:—“There are persons who love to hold their knowledge for themselves alone, and to be the reputed possessors and guardians of secrets. People of this kind grudge the public everything, and if any discovery, by which art and science will be benefited, comes to light, they regard it askance, with scowling visages, and probably denounce the discoverer as a babbler who lets out mysteries. But why should such secrets be grudged to the public? Why withhold from this enlightened age? Whatever is worthy to be known, should by all means be brought to the great and general market of the world. Unless we do this, we can neither grow wiser nor happier with time.” These are true, liberal, and noble words.