In fairness, I think they were trying to point out that the idea there might be a correlation between intelligence and depression has been around for a long time:

"Aristotle introduced a quantitative factor, asserting that levels of melancholy and black bile are positively correlated; however, under a given threshold of black bile, it can give rise to an exceptional being"

The fact that Aristotle thought "black bile" was responsible for both is neither here not there, but just a necessary context to understand the quotation.