In the summer of 1721, Swedenborg started again on his travels, his object this time being to study the mines and manufactories of other countries, so that he might be in a position to render greater services to his own in the office to which he had been appointed. On this occasion he visited all the mines in Saxony and the Hartz mountains, and was royally entertained by Duke Ludvic Rudolf of Brunswick-Lüneburg, who showed him a generosity which he doubtless appreciated after his father’s parsimony. Meanwhile his pen was by no means idle. He published a treatise at Amsterdam on Chemistry and Physics; some observations on Iron and Fire; and a work on the construction of Docks and Dykes; and later on, at Leipzig, some miscellaneous observations on Geology and Mineralogy. On his return home he settled down again for a period to his work at the Board of Mines, in the meantime gathering matter for further publications which followed in due course. The most important of these were his _Opera Philosophia Mineralia_, and a treatise on _The Infinite_. The former work met with a very favourable reception, and between one publication and another Swedenborg soon won for himself a European reputation. The Academy of Sciences at St Petersburg nominated him a corresponding member, while he was one of the first to be elected for the newly established Royal Academy of Sciences in his own country. Everything thus seemed to open out for Swedenborg a career of great scientific and practical utility. He became, however, gradually led by his philosophical speculations to an investigation of the nature of the soul and its operation in the body, and the mutual relations of the two. This study was the subject of two important works, entitled respectively _The Economy of the Animal Kingdom considered Anatomically and Philosophically_, and _The Animal Kingdom considered Anatomically, Physically, and Philosophically_. By the “animal kingdom” must be understood the kingdom presided over by the soul. In the first of these books Swedenborg deals with the composition of the blood and its circulation, with the heart, arteries, and veins, and with the brain and its cortices. In this book Swedenborg attaches “great importance to the blood, for, as he says, nothing exists in the body that has not previously existed in the blood.” He describes it again as “a vital and most spirituous fluid, which has an immediate connection with the soul.” In the _Animal Kingdom_ Swedenborg describes in full detail all the organs of the body and their uses, the object being in the end to track the soul home and to describe its activities. “For as yet,” he tells us, “her modes of being and her nature are absolutely unknown.” Naturally he recognises that this will be regarded by the philosophers of his day as a vain and useless quest. But he is prepared to meet their objections with the following pertinent remarks, which, now that the materialistic