As a monopolist lowers the price of its product from a high level, it finds that its total revenue may at first increase and then, below a certain price, its total revenue begins to decrease.

This is because, initially, the increase in quantity sold due to the price decrease can more than offset the lower price, raising total revenue. However, beyond a certain point, further price decreases lead to a smaller increase in quantity sold that does not compensate for the lower price, causing total revenue to decrease.