sensitive soul which is the husk or shell of the immortal mind. Before the Fall the archeus obeyed the immortal mind and was directly controlled by it, but at the Fall men also received the sensitive soul and with it lost immortality, for when it perishes the immortal mind can no longer remain in the body. Van Helmont described the archeus as "aura vitalis seminum, vitae directrix" ("The chief Workman [Archeus] consists of the conjoyning of the vitall air, as of the matter, with the seminal likeness, which is the more inward spiritual kernel, containing the fruitfulness of the Seed; but the visible Seed is onely the husk of this."). In addition to the archeus, van Helmont believed in other governing agencies resembling the archeus which were not always clearly distinguished from it. From these he invented the term blas (motion), defined as the "vis motus tam alterivi quam localis" ("twofold motion, to wit, locall, and alterative"), that is, natural motion and motion that can be altered or voluntary. Of blas there were several kinds, e.g. blas humanum (blas of humans), blas of stars and blas meteoron (blas of meteors); of meteors he said "constare gas materiâ et blas efficiente" ("Meteors do consist of their matter Gas, and their efficient cause Blas, as well the Motive, as the altering"). Van Helmont "had frequent visions throughout his life and laid great stress upon them". His choice of a medical profession has been attributed to a conversation with the angel Raphael., and some of his writings described imagination as a celestial, and possibly magical, force. Though Van Helmont was skeptical of specific mystical theories and practices, he refused to discount magical forces as explanations for certain natural phenomena. This stance, reflected in a 1621 paper on sympathetic principles, may have contributed to his prosecution, and subsequent house arrest several years later, in 1634, which lasted a few weeks. The trial, however, never came to a conclusion. He was neither sentenced nor rehabilitated. Observations on digestion Van Helmont wrote extensively on the subject of digestion. In Oriatrike or Physick Refined (1662, an English translation of Ortus medicinae), van Helmont considered earlier ideas on the subject, such as food being digested through the body's internal heat. But if that were so, he asked, how could cold-blooded animals live? His own opinion was that digestion was aided by a chemical reagent, or "ferment", within the