Swedenborg had set out on his fifth foreign journey in July, 1743, for the purpose of publishing The Animal Kingdom. He had left Stockholm on the 21st, arriving five days later at the port of Ystad in southernmost Sweden. Here, with other distinguished travelers, he waited until August 5 for a favorable wind. Early the next morning the party arrived at Stralsund in Pomerania, where Swedenborg joined his nephew Carl Jesper Benzelius for a few days' visit to places of interest. Arrived in Hamburg, he had the pleasure of meeting His Royal Highness Adolf Friedrich of Holstein-Gottorp who the previous month had been chosen successor to the Swedish throne. During his talks with the future monarch, Swedenborg showed him the Table of Contents of his proposed book, and the generally favorable reviews of his Economy.
Traveling from Hamburg to Bremen toward the end of August, 1743, he passed for miles through a charming countryside heavy with its summer burden of pears, apples, plums, walnuts and chestnuts. After his arrival in Amsterdam his Journal of Travel abruptly breaks off. Some four leaves are missing, perhaps intentionally removed. The remaining portion is devoted to recording some remarkable psychic experiences that were profoundly to affect the remainder of Swedenborg's life;-but of this later.
He spent the autumn in Amsterdam, preparing his Animal Kingdom for the press, consulting authorities on anatomy, visiting the nearby university of Leyden, and writing the Prolog to the first volume which treats of the organs of digestion. In December he took the manuscript to his printer at The Hague.
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Swedenborg now seems to have come to realize the limitations of the reasoning faculty. Rational arguments, clear as crystal to one mind, had not the slightest effect upon another! The truth seems to have dawned upon him that, as a path to faith, arguments were insufficient. Why was it that one could not convince another by reasoning, be it ever so sound? His entry upon the empirical method had come after Professor Celsius had challenged his methods in the Principia. Swedenborg did not admit that he was very much in error there, but the criticism of a fellow member of the new Academy of Sciences may have influenced him, in working out his next scientific work, to try the analytical approach. Possibly, in so doing, he thought he might convince them by using their own methods, and so overcome their opposition by the weapons of their own choosing.
He had now come to the end of the road as far as the process of analysis could take him. A different method, indeed a new vessel, had to be chosen for the remainder of his voyage into the unknown. Indomitably, for some ten years, he had pursued the study of human anatomy in quest of the soul, only to find that he had come but to the inner shrine of the living body! For although he knew the secrets of the human mechanism better than any man of his day, although he well understood its hidden modes of acting, still he had not reached the Soul herself. In a manuscript entitled De Anima (The Soul) intended as the seventh part of The Animal Kingdom, and posthumously published as The Rational Psychology  - Swedenborg acknowledges that he must treat the soul, not from experience or effects, but from first principles, that is, a priori. The soul is,' indeed, "invested with a toga" from the interior spheres of nature, it is indeed present in the body as "inmost blood" or "spirituous fluid." But being a spiritual essence, an immaterial thing, the attempt to reach it will be vain without the assistance of first principles. For although analysis -the study of phenomena with the aid of the sciences-is the only way open to the human race for obtaining knowledge of natural things, still, by this method, one can obtain no real truth without the influx of a higher power.
In one sense The Rational Psychology is the fulfillment of Swedenborg's goal. In this work he indeed arrives at the soul as far as concerns its relation to the body. But only so far. This relationship he saw as one of instinctive harmony, to which he gave the name of "correspondence." The soul's mode of operation upon the body he saw as an influx or inflowing of the higher faculties into the lower faculties. Take, for instance, the emotion of joy. This originates in the cortical glands, the beginnings of the fibers. It expands these little vessels. It flows into the fibers and these also are expanded. Finally it diffuses itself into the face where the joy becomes visible in an expansion of the countenance, an expression of gladness. Hatred, on the contrary, compresses the brain, vitiates the bloods and causes the muscles to contract.
The substance of the soul was still a secret, but its mode o f communication with the body seemed clear to him. This had been the definite object of his quest throughout the anatomical studies. He now knew how the soul worked. He saw it acting by means of the faculties of sensation, imagination, thought, and will, saw it operating upon the five senses by inflowing into the minutest vessels and fibers of the brain. It appears as if the outer senses acted upon the soul, but this is a fallacy. Sight exists in the mind, not in the eye. The relationship between the soul and the body is one of harmony, or correspondence. When outer things are in harmony and agreement with inner things, they respond and are able to act as one!
Swedenborg recognized in the soul two distinct degrees, - a lower mind which he calls the animus, and a higher or rational mind which he calls the mens. The animus is the seat of sensations. Proper to it are the "affections" (emotions) such as gladness, sadness, venereal love, parental love, friendship, ambition, humility, contempt, love of fame, generosity, magnanimity, avarice, prodigality, fear, pity, bravery, shame, revenge, mental tranquility, impatience, cruelty, intemperance, temperance, frugality, and so on. The mens, or higher mind, is the life of thought, as the animus is that of emotion.
In the cortex of the brain, sense-images are turned into ideas. When reproduced in the imagination, they are memory: Each cortical gland contains a web or texture of almost inconceivable fineness, a "simple cortex." This is the origin of "the simple fibers" and the seat of "the pure intellect," in which resides the faculty of understanding. This is the beginning of all human things, and upon it they all depend. It is born of the inmost soul (anima), and issues all judgments and decrees.
In this work Swedenborg discusses the relationship of soul to body. He recognizes also another side-the relation of the soul to "heavenly society," to immortality. Of this he knew very little, and this little he expressed in vague conjectures. But his thirst for knowledge was more ardent than ever. He hopes in a few years to be in a position to declare what would be the state of the soul when its connection with the body is severed. As to what would be the soul's form after death he had no clear ideas at this time, as is evident from the following passage:
Swedenborg did not publish his Rational Psychology. Perhaps he felt that, in a certain sense, the soul had eluded him. He aimed at less attainable goals than those of modern psychology. Testing and measuring the intelligence interested him not at all, nor did the application of such findings to practical life. He knew that the learned of his day were not following him, and would reject the best of what he had to offer. He knew that analysis, the very method which had carried him so far into anatomy, now no longer sufficed. The top of the mountain had indeed been reached, and further ascent was possible only into the sky. He knew that he had to look for guidance to an inner source and this involved not argumentative reasoning, but discernment-an intuitive faculty.
In order to follow Swedenborg's development here, one must reflect on the nature of this faculty. Intuition is definable, in the last analysis, only by individual experience. Everyone, however, resorts to intuition, or inner guidance, when no other way is open. The wrecking of a ship in mid-ocean, the crashing of a plane on a mountain top, may bring the victims comfort from relationships that before and afterward seem unbelievable, remote and irrational. In choosing a mate one relies on an impulse deeper than thought and listens to an inner voice saying "mine." When presented with new views on religion, the convert's mind - when finally fixing itself in the idea "true" - turns to a light brighter than that of reason. Perception, affirmation, conviction, all told Swedenborg that he must look "within" for the assurances of truth.
That there was another realm, another world, in which the relationships between immaterial things are just as real as are physical relationships on earth, Swedenborg never doubted. He could not have imagined that the phenomena of that world would soon become familiar experiences to him, yet he must have been convinced that he was at the very threshold of that world, for he began to experience a series of remarkable dreams, and a super-sensory life of extraordinary richness and power began to emerge as an orderly part of his development.
Experiences of the sort called supernatural were not new to him. Ever since 1736, as we know, Swedenborg had seen flashes of light, flames, that he took as confirmatory signs betokening the approval of an intelligence not of this world. But now these tokens began to have a more definite meaning and to give greater direction to his life. This seems to be entirely in line with his mental growth, intimately related to the application of his new philosophical doctrines to his work. For mark the progression of ideas!
The Principia had been based foremostly on a doctrine of order as applied to "finites" and "atmospheric particles." In the Economy he had applied the doctrines of series and degrees - the series of organs and the degrees of the bloods. In The Animal Kingdom, in treating of the bodily organs and their uses - as for instance the glands and the lungs - he had especially developed a doctrine of integration which he termed the doctrine of society. In its continuation, The Brain and The Soul, he had applied the doctrine of influx. Until now, however, as he explicitly states, he had not greatly developed the concept of correspondences and representations. In his groping for this sublime doctrine, Swedenborg approximated it in his search for "a co-established harmony," for "a universal science," for "a hieroglyphic key."
This concept is essential for understanding the phase of Swedenborg's life that now ensues, for it enabled him to see a relationship between the objects represented to him in dreams and their equivalents on a higher plane. He thus arrived at a means of interpreting his dreams without which they would have had little if any value. It was an attempt to formulate a new symbolic logic, whereby a known natural law could be transposed to a higher power, making a spiritual law, applicable to the mind or to the realm of theology. He saw the possibility of expressing, almost in terms of algebraic formulae, the relationship between natural things such as light, speech, blood, pain, and their counterparts on an abstract plane - where light becomes intelligence, speech becomes thought, blood becomes spirit, and pain becomes anxiety. Material things were thus seen to have -reference to immaterial things, far and above their value as mere poetic imagery and yet related to it.
This was the beginning of that "science of correspondences" which was to become an integral part of . Swedenborg's future system. This link between the physical and the supernatural is contained in a little work found among his unpublished manuscripts entitled The Hieroglyphic Key. It has little or nothing to do with hieroglyphics and is not properly a key, but it contains the raw material from which a key was later to be fashioned. The relation between things material and immaterial is here brought out but in an incomplete, preliminary manner.
It must not be supposed that the idea of correspondence or the "answering" of one thing to another-thing-on-a-different-plane, was entirely original with Swedenborg. It did not spring from his brain in full regalia like Athene from the head of Zeus. Others before him had felt that there exists such a connection between two worlds, one the world' of the senses, the other a world above the senses. Dr. Martin Lamm, in his penetrating biographical study, has done scholars a great service in carefully tracing out the possible sources from which Swedenborg could have derived hints regarding the doctrine of correspondences.
Many suggestions for the concept came through Aristotle and Plato and other classical writers plentifully quoted, especially in The Economy. But still more clearly may we trace the antecedents of Swedenborg's ideas on this doctrine through the Neoplatonist movement which arose in the third century. The highest object of Neoplatonism was to combat reliance on empirical knowledge alone, and to develop the philosophy of revelation as something supra-rational. Its chief exponent was Plotinus, a writer not unknown to Swedenborg. Revelations of the Deity, said Plotinus, are found in the religious traditions and rites of all nations. In history, everywhere, there are instances of God's revealing of His Spirit. The Neoplatonists therefore attempted to reconstruct the ancient religions and to explain polytheism by regarding the worship of images as the result of an inherent sympathy between the higher powers and the images under whose forms those powers were worshipped. The teaching had its origin in Alexandria, and was not a Christian philosophy, but ideas from it flowed into Christianity like the warm currents of a gulf stream, tempering and coloring the cold rationalism of severely literal creeds. Those who fell under its influence taught that the only blessedness that can satisfy the human heart must be sought in a sphere higher than reason. The Supreme Being can be reached only through "ecstacy," they said, since God is elevated above the plane of reason. They taught that the human soul has departed from its first estate and must find the way back through self-renunciation. They taught that there are three worlds, the highest being Divine, the second an ideal world of souls, the third the familiar phenomenal world.
Swedenborg's -mind was that of a scientist, trained to abstract construction and exact methods, and so the intuitions which the mystics and visionaries had put forth in a manner that was vague and occult, became in his mind reduced into a system. He never demanded that his readers should merely believe him, but always that they should understand him. Nor did he, at this time, consider that he had any more knowledge of such things than others had. Discussing what will be the form of the soul after death, he says:
The reason why knowledge of its future state is now hidden from the soul and why things well known in former, more enlightened days, are now so fragmentary and obscure, is that wisdom must come into the soul by influx from above, and such influx cannot operate into minds where the fires of self-love and bodily pleasures rule and where the lust for power is burning brightly. The fires of self-love must first be extinguished before this sublime source of intuition can be opened up, for otherwise the reception of higher light is retarded-a law that we will see operating very particularly in Swedenborg's own case 269 It is just here that he distinguished himself from the mystics of his day when the influence of Jacob Böhme was very great, especially in Germany. Over the entire religious world there hung an atmosphere of unclear thinking which penetrated men's minds like an inescapable fog. Prophetic dreams, visions and revelations were everyday occurrences, and the courts and consistories held daily sessions, often passing cruel sentences on innocent and excellent Christians. The extreme form which fanatical pietism sometimes took was encountered by Swedenborg in Copenhagen where he noted in his Journal of Travel:
Swedenborg has stated that he never read the writings of Böhme and Dippel, yet he is often considered to have fallen under their spell. His aim was the same as theirs but his approach was entirely different. There is not a trace of mysticism in his Principia, for connectedness and reason were the keynotes of his philosophy.
In The Hieroglyphic Key he discusses many kinds of correspondences but he makes no claim to having succeeded in bringing them into a complete system. He mentions images and types, likenesses and allegories, fables and oracles, and his final conclusion is: "We are justified in believing that the universal world is wholly filled with types, but we know very few of them." However, like a signpost pointing to the future, his last statement is: "It is allowable thus to interpret Sacred Scripture, for the spirit speaks naturally and also spiritually."
Swedenborg was probably convinced that his next step would have to involve a study of these things. In a note in The Animal Kingdom he deals with the function of the kidneys in purging the blood of impurities, which typifies that purification of the spirit which every man must undergo in the process of regeneration. Boldly he declares:
Equally dangerous for him now were the treacherous eddies of mysticism which drew the unlearned of his day, and the rising tides of denial on which the learned were drifting, pulled by materialism and the irresistible trends of self-guided intelligence. Both these ways of thinking exerted their attractions upon Swedenborg, but he chose to give his allegiance to his new philosophical doctrines, and steadfastly set his course by the compass of Faith.
It was not always easy sailing. He was pulled hither and thither. A storm of inner conflict was brewing. The shore line disappeared. The elements raged. At times his ship seemed about to founder. The period of crisis closed in on him which we find so vividly recorded in his Journals for the years 1743 and 1744.