In 1611 printed material was common and inexpensive, because printed material was inexpensive literacy was high, and because printed material was inexpensive more literate people knew English than knew Latin.
In 1400 manuscripts were scarce and expensive, because manuscripts were scarce and expensive literacy was low, and because manuscripts were scarce and the vast bulk of manuscripts were transcriptions of Latin originals if you were literate in 1400 it meant that you read Latin.
By 1648 Europe was divided into ethnic states that had their own separate languages as instruments of nationalism. In 1400 Europe was a patchwork of multiethnic kingdoms and princedoms and republics that used Latin as the common language of communication among the educated.
Between 1450 and 1550 you had the rise of nationalism, the wide availability of paper (as opposed to expensive animal skins) and the invention of printing - developments that completely altered European notions of education, literacy, language and politics.
It was always a problem for people of conscience to determine for themselves a thought process without the input of knowledge.
Knowledge was often dictated according to a pre-supposed result.