Book Description from Wikipedia:
Political Man: The Social Bases of Politics is an
award winning political
science book by Seymour
Martin Lipset. The book is an influential analysis of the bases of
democracy across the world. One of the important sections is Chapters 2:
"Economic Development and Democracy." Larry Diamond and Gary Marks
argue "Lipset's assertion of a direct relationship between economic
development and democracy has been subjected to extensive empirical
examination, both quantitative and qualitative, in the past 30 years. And the
evidence shows, with striking clarity and consistency, a strong causal
relationship between economic development and democracy."
Excerpt from the book concerning "political legitimacy":

