Final answer:
The paragraph chiefly aims to inform readers about historical ailments stemming from a lack of knowledge regarding the dangers of certain materials, such as mercury and lead.
Step-by-step explanation:
The primary purpose of the paragraph is to inform readers about ailments that were historically misunderstood and could have been avoided with more knowledge. Through examples like the mercury poisoning of hat makers leading to symptoms such as trembling and mental confusion, and the lead in painters' materials contributing to depression, the text illustrates how ignorance of certain hazardous substances negatively impacted people's health. The paragraph does not, however, seem focused on persuading readers to protect themselves against such ailments, but rather on highlighting the unfortunate consequences of a lack of knowledge in the past.