Answer:
The two sources are telling us that Medicine in the medieval period was highly speculative, often based on primitive or ancient beliefs since doctors lacked scientific knowledge about the human body.
Both sources make reference to the practice of medieval doctors of "examining" a patient's urine, and act that the writer of the first source accuses of having been mere speculation, arguing that all the doctors knew was that they were holding urine, and that they made up the rest along the way.