The dissertation discusses the life and work of Ernst Soner (1573-1612), professor of natural philosophy and medicine at Altdorf. It is based on Soner's inauguration speech De Theophrasto Paracelso euisque perniciosa medicina (1605), and, used for its interpretation, his later publications, as well as Soner's recently discovered handwritten Socinian catechism. Soner, a covert heretic, educated by heterodox Aristotelianism and rationalistic Socinianism, in his inauguration speech appeared as a defender of academic tradition. The irrationalism and spiritualism of the Paracelsists served Soner to create an expedient image of his adversary. According to Soner, scientific and religious cognition arises from a multiple gradual process, composed both of induction and deduction, as well as empiricism and logic. Nevertheless the legitimacy of tradition (ancient writings, the Bible) is ensured by the historic principle of consensus and effectiveness. Any form of matter (primary matter, heaven, sublunary elements) is marked by corporality, and is identical with being. The material division of the spheres into the divine, astral and sublunary, may be overcome only by human reason. Soner renounces the existence of the divine substance in objects and rejects Paracelsists' 'balm' (divine essence of things) and 'tria prima'. Because of the natural boundaries of human life, Soner points out the illusiveness of the Paracelsists' hope for the 'chemiatric path' to acquiring immortality. In Soner's philosophical writings God is characterized as a rational contemplative being. The postulated division into the divine and human spheres results in emphasizing human mortality and susceptibility to illness before the original sin. Jesus Christ was also a human. His supernatural qualities (immaculate conception, resurrection, the offices of mediator and ruler) were due exclusively to the divine grace. The Lord's Supper should be understood as a symbol: it serves exclusively to commemorate and foretell the Christian community. Here we may detect a parallel with the rejection of the Paracelsists' 'balm'. Soner's catechism represents his consistent unitarianism. Jesus Christ - a Man, received his power from God, and the Holy Spirit represents only the divine power.