a view on the organization of natural things based strictly on chemistry. Such a view, he wrote, "resolves all Bodies into Particles of Spirit, Sulphur, Salt, Water, and Earth ... Because this Hypothesis determinates Bodies into sensible parts, and cutts open things as it were to the life, it pleases us before the rest." Willis derived many of his conclusions from observations on distillation. It was eventually realized that these explanations were not accurate. Natural philosopher Robert Boyle contributed greatly to the understanding of respiration by showing that air (or oxygen), which is required for fire in combustion reactions, is also needed for human breathing.[1] Despite this, Boyle's works on the mechanical origin of qualities were generally rather remote from Helmontian chemistry; however, Boyle's philosophy and Helmontian iatrochemistry were not mutually exclusive. Like van Helmont, Boyle claimed that spirit of human blood, like other ingredients obtained by the chemical analysis of blood, was no simple substance. Challenge to Galenic physiology Iatrochemistry was a new practice in the 17th century, a time when traditional medicines were based on a legacy from the 4th and 5th centuries B.C. Much of this tradition was derived from Galen and Avicenna. The iatrochemists rejected the traditional medical theory, mostly from Galenic traditionalists. Galen traditionalists sought to establish the balance of temperament within the bodies. There are two pairs of qualities, hot and cold, and wet and dry. Sickness came from the imbalance of one quality. That is, a cold was an excess of heat (hot quality), so it can be cured by reducing hot quality or by increasing cold quality. The iatrochemists, influenced by Paracelsus's belief, believed that the sickness was from the outside source, not because of the imbalance of the body. Another controversy between Galenic traditionalists and iatrochemists was the way to use herbs. The Galenic traditionalists thought that the strength of remedies relied on the amount of plant materials that was used. The iatrochemists, however, supported the chemical preparation of materials of remedies to increase the effectiveness of the materials or to find the stronger medicine. Additionally, Galenic traditionalists argued that chemically prepared medicines were poisonous, and the iatrochemists were inadequately trained. The former was true, and, in some cases, both were correct. Since Paracelsus claimed that poisons could have beneficial medical effects, the number of toxic ingredients used in chemical medicines had increased. Galenic traditionalists later adapted medical method and some