The relation between Emanuel Swedenborg and Immanuel Kant has been the subject of many discussions. The chief aim of this paper is not to elucidate this question from an historical point of view, but to compare the teachings of the two thinkers, as those teachings have come to us. Kant's "Träme eines Geistersehers" embodies a very unfavourable opinion about Swedenborg. It is a curious circumstance, that this judgement is not based on decisive arguments. On the contrary, Swedenborg's fundamental doctrines about (...) the existence of a spiritual world and the communication between the living and the dead, are accepted by Kant as plausible. Du Prel and others have concluded, that Kant was a Swedenborgian in his heart, and that his negative attitude was due to the fear of losing his scientific reputation. A careful consideration of the two philosophical systems does not tend to bear out this opinion; nevertheless, such a comparative study is very instructive. In the mental development of the two thinkers there are remarkable analogies. Both were occupied with the great problems of God and the human soul; and both were disappointed by the leading philosophical and theological doctrines of their days. To Swedenborg those doctrines seemed to lead straightforwardly to naturalism and atheism. Kant was struck by the diversity of the opinions expressed and by the succession of heterogeneous doctrines without lasting results. But the reactions of the two men in these circumstances were different. In his cosmological and anatomical works Swedenborg aims at acquiring a comprehensive view of the Universe, in which view God and the soul should obtain their proper places. When he had reached the age of about 55 years, a crisis set in, which he described as "the opening of his spiritual senses". From that time he could see the spiritual world and speak with its inhabitants; he could study the workings of God and of the soul with the help of living experience. Kant raised the question, whether there are departments of knowledge in which certainty is attainable, and what is the ground of this certainty. His answer is, that the fundamental propositions of mathematical physics are absolutely certain. The ground lies in the fact, that these propositions are not derived from experience, but that they are "synthetic judgments a priori". They express the workings of the "categories" and "forms of intuition". by means of which the mind constructs, out of a chaos of sense-impressions, the ordered universe of science. Of objects to which these propositions do not apply, e.g. God and the soul, no certain knowledge is possible. This precludes the knowledge of "another world", fundamentally different from our ordinary world. So there seems to be an irreconcilable opposition between the teachings of Kant and of Swedenborg, But further considerations tend to lessen this contrast. Notwithstanding his own teaching, Kant accepted a life after death and he even speculated on it. If we follow this example, we come to remarkable conclusions. It is reasonable to suppose, that the spirits, who have been men, use the same categories as we do. Then out of the impressions which reach them, they will construct a world built on the same pattern as our earthly world. So life before and after death will not be very different. And this is precisely Swedenborg's teaching. This may be confirmed by the experiences of our dream-life. In dreams, our mind out of different impressions builds a world closely resembling our ordinary world. The spiritual world, as described by Swedenborg, presents many analogies with the world of our dreams. Now it is a very remarkable circumstance, that modern physics has been under the necessity of modifying the system of categories as described by Kant. In quantum mechanics the connection between cause and effect is less stringent than in classical mechanics. This adds fresh interest to the study of a system like that of Swedenborg, where quantitative laws are largely replaced by qualitative laws. (shrink)