who introduced the earliest belief that life was spontaneously generated from nonliving matter
Abiogenesis Belief in spontaneous generation of certain forms of life from non-living matter goes back to Aristotle and ancient Greek philosophy and continued to have support in Western scholarship until the 19th century.[76] This belief was paired with a belief in heterogenesis, i.e., that one form of life derived from a different form (e.g., bees from flowers).[77] Classical notions of spontaneous generation held that certain complex, living organisms are generated by decaying organic substances. According to Aristotle, it was a readily observable truth that aphids arise from the dew that falls on plants, flies from putrid matter, mice from dirty hay, crocodiles from rotting logs at the bottom of bodies of water, and so on.[78] In the 17th century, people began to question such assumptions. In 1646, Sir Thomas Browne published his Pseudodoxia Epidemica (subtitled Enquiries into Very many Received Tenets, and commonly Presumed Truths), which was an attack on false beliefs and "vulgar errors." His contemporary, Alexander Ross, erroneously refuted him, stating: "To question this [Ed.: i.e., spontaneous generation], is to question Reason, Sense, and Experience: If he doubts of this, let him go to Ã†gypt, and there he will finde the fields swarming with mice begot of the mud of Nylus, to the great calamity of the Inhabitants."[79][80]
Germ theory of disease Microorganisms are said to have been first directly observed in the 1670s by Anton van Leeuwenhoek, an early pioneer in microbiology. Yet Athanasius Kircher may have done so prior. When Rome was struck by the bubonic plague in 1656, Kircher spent days on end caring for the sick. Searching for a cure, Kircher observed microorganisms under the microscope and invented the germ theory of disease, which he outlined in his Scrutinium pestis physico-medicum (Rome 1658).[16] Building on Leeuwenhoek's work, physician Nicolas Andry argued in 1700 that microorganisms he called "worms" were responsible for smallpox and other diseases.[17]