Final answer:
The section 'size versus impact' discusses the optimal balance between corporate size and market competition, and the government's role in this dynamic.
Step-by-step explanation:
The main idea of the section “size versus impact” in source 3 deals with the balance between large corporations and the number of competitors within a market. It critically examines the optimal mix of corporate size versus competition and what role the government should play in regulating or supporting this balance. The section also ponders individual actions and values and how they can cumulatively lead to significant impacts. It contemplates the governmental policies that could either provide individuals with ways to contribute positively to the economy or control the extent of corporate influence and competition.