Final answer:
In his speech, William Jennings Bryan argued against the Republican belief that the gold standard was crucial for American prosperity, advocating for a bimetal or silver standard instead to benefit working class and farmers.
Step-by-step explanation:
The main point of the speech "Cross of Gold" by William Jennings Bryan was to argue against the Republican stance that the gold standard was the only way to ensure stability and prosperity for American businesses. Bryan believed that moving to a bimetal or silver standard would benefit the working class and farmers. He emphasized that the backing of gold would put unnecessary financial burden on labor and ultimately crucify mankind.