During the 16th century there were some 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] in medicine. However it remained basically the same as in the Middle Ages. Medicine was still dominated by the theory of the four humours. In 1546 a man Girolamo Fracastoro published a book called On Contagion. He suggested that 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] diseases were caused by 'disease seeds’, which were carried by the 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind or transmitted by touch. Unfortunately there was no way of testing his theory.
In 1478 a book was printed by Celsus. It became the new standard text book but his ideas were challenged by 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] (Theophrastus von Hohenheim). He called himself Paracelsus (meaning beyond or surpassing Celsus). He denounced all medical teaching not based on 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] and experience. Paracelsus rejected the idea that disease was caused by an 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind of humours. He said that disease resulted from problems with 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] inside the body. Since the cause of disease was chemical, treatments should be chemical. He experimented with salt, sulphur and 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind.

This shows that the Renaissance began a period where although classical ideas were used, they also questioned these and a new spirit of 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind began.
However there are still examples to be seen where the old ideas persisted as in the use of 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind and bleeding based on the Four Humours. When 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind became ill in February 1685 with symptoms of headache and loss of speech his treatment was based on old methods of healing rather than newer techniques. This was surprising as the 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind had begun with the sponsorship of Charles. He was treated by bleeding and purging which inevitably led to his 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?].

Another individual of the Renaissance was William 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind, a physiologist who realised that the heart is a pump. Each time it contracts it pumps out blood. Harvey then estimated how much blood was being pumped each time. 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind believed that the body constantly makes new blood and uses up the old. However Harvey realised this is not true and instead the blood circulates around the body. Harvey's discovery eventually proved the keystone of 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] medicine. From his time onwards the theory of the four 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind slowly declined. Unfortunately it took a long while to die out completely.
The discovery of the 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind and scientists looking at capillaries and cells under it showed that new ideas were evolving. In 1683 Antoine van 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind observed microorganisms. However he did not realise they caused 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind.

For most of history, medicine has been more an art than a science It was only in the 19th century that science had any significant impact on its practice. This is demonstrated with the history of blood- letting. Even William Harvey's discovery of the 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind of the blood didn't restrict blood-letting which continued as a general practice.
Blood letting has been an important medical tool throughout history. In the medicine of Hippocrates and Galen its purpose was to release excesses of humours and balance the body's humour levels in order to 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] disease. In the 1500s blood letting was considered one of the best ways for treating 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?], and in 1812 Benjamin Rush wrote on the treatment of mania:
"The first remedy under this head should be blood letting. It should be copious on the first attack.... From 20 to 40 ounces of blood may be taken at once.... The effects of this early and copious bleeding are wonderful in calming 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] people."1
The nineteenth century saw further theories of disease. The 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind theory which had been around since the sixth century was at the forefront but now they were not thinking about covering up smells but rather fumigating them. Another theory of disease, that of 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind generation, was also wrong, and had to disproved by Louis Pasteur.
By 1924 with the advent of new medical theories such as 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind[?] and the rise of more complex surgical procedures blood counts became routine. Although some blood transfusions had been attempted in the 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind, it was not until after 1650sbacteriologyCharles IIchemicalscirculationcuredeathdiseaseexperimentGalenHarveyhumoursimbalanceimprovementsinfectiousLandsteiner'sLeeuwenhoekmadmercurymiasmamicroscopemodernParacelsuspurgesscienceScientific Revolutionspontaneoussyphiliswind discovery of blood groups in 1900 that doctors started to attempt to put blood back in to their patients.