One reason why Burton’s book vexes readers might be because of its subject matter. Melancholy is not an easy concept to clearly define. It’s an elusive mix of sadness, despondency, dispiritedness, gloom, misery, anxiety, and so on. Burton quips that it’d be easier to “find the motion of a bird in the air, as the heart of a man, a melancholy man.” Indeed, the intangible traits of melancholy make Burton’s book tough to grasp.
Concerning the specific subsection noted in the question—“Love of Learning, or overmuch study”—Burton attempts to identify why scholars and students are particularly susceptible to the perplexing but potent malady known as melancholy. According to Burton, study weakens bodies, dulls spirits, and zaps courage. Scholars tend to live solitary lives. Their isolation makes them vulnerable to attacks of melancholy. Burton heeds the belief that too much knowledge can make a person mad. The fact that study doesn’t lead to explicit rewards, like other professions, reinforces its melancholy foundation.
To make his points, Burton brings in numerous examples and thinkers. He mentions an Italian philosopher, and he includes a quote from Seneca the Younger, as well as the mythical ruler Aeneas Silvius. If Burton’s book was a blog post or an online article, it’s safe to say that it’d feature links to numerous other sites and pages. Burton’s anecdotal, digressive manner doesn’t make his book any easier to read. However, its dense style doesn’t mean that it isn't insightful or that it can be dismissed.