In canto XVII of Inferno, Dante anticipated the principle of Galilean invariance 300 years before Galileo. Even earlier, Islamic steelmakers in Damascus unwittingly exploited nanotechnology in the manufacture of sabres that became the envy of the world. So the middle ages weren't so medieval.
Almost the only annoying thing about James Hannam's admirable book is his opening insistence on a conspiracy of "popular opinion, journalistic cliche and misinformed historians" to denigrate the middle ages, and he cites the compass, Columbus and the 1455 printed Bible of Gutenberg as advances of the middle ages. In this conspiracy, whenever someone discovered evidence of reason or progress in the 14th or 15th centuries, he writes "it could easily be labelled 'early-Renaissance' so as to preserve the negative connotations of the adjective 'medieval'." The OED gives no dates for the medieval period, but it tells me that the Renaissance began in Italy in the 14th century.