Starting at page 177:
http://bchistorycore.wikispaces.com/file/view/The+Black+Death.pdf#page=177
The science of the Black Death according to a man of the time. The thing is, his explanation sounds scientific, and he even addresses the objections (which themselves were good) relatively well (though he employs a few fiat and circular arguments).
I think it gives you some pause and makes you consider science and how certain we are in some things.