1. PHLOGISTON
In 1669 , alchemist Johann Joachim Becher propose that attack was because of an element called phlogiston . Anything you could set alight , he claimed , contained this substance and the only way to put a blast out was to “ dephlogisticate it”—that is , burn it to ash . This hypothesis rule for nearly 100 years , until Joseph Priestley debunked it by discovering a lilliputian thing called oxygen .
2. SPONTANEOUS GENERATION
For ancients like Aristotle , the maggot that wrestle out of stinking heart and soul were living test copy that life could bloom at random . As of late as the 1600s , Belgian scientist Jan Baptista van Helmont had a formula for making mice : “ rate a sordid shirt or some rags in an heart-to-heart pot or barrel moderate a few grains of wheat or some wheat bran , and in twenty - one days , mice will appear . ”
3. MIASMA THEORY
Until the mid-19th century , people trust forged sense of smell were a toxicant mist of decomposed matter that do disease . It was n’t until the 1860s that germ theory revealed that microorganisms are actually to blame . However , the mind that the world was full of unseeable living thing seemed so outrageous that for decades MD debated the necessity of wash their manus .
4. MATERNAL IMPRESSION
Up until the early 1900s , some doctors believed that a pregnant char ’s thoughts and experiences could stimulate birth fault . For example , if she take care a man lose a hand in a pale yellow thrasher , the shock could cause her child to be born with a stump . Joseph Merrick ( a.k.a . “ the Elephant Man ” ) believed his deformities were the resultant role of his mother being fright by a fairground elephant .
5. EMISSION THEORY
A lot of very smart people — from Plato to Euclid to Ptolemy — believed that we see things because our eyes shoot out beams of light . Of course , this is backward : We see because light enroll our eyes . But the thought persisted nevertheless for at least 10 100 : A 2002 study found that up to 67 percent of college student think eyes utter rather than receive light .
