Central America's radical intellectuals usually combine theory and praxis. The radical intellectuals contemplate, discover, clarify, or bring new ideas or theories to the attention of the intelligentsia. Radical thought has antecedents in ancient Greece, where the philosopher Heraclitus advanced the idea that materialism affected social relations. The radical goes beyond mere espousals of militance and independence and seeks social justice, equality, and a more even distribution of wealth. The overwhelming majority of Marxist and non-Marxist radicals prefer electoral and participatory democracy and constitutionalism. Karl Marx laid the concept of praxis as a foundation block of socialist thought, Lenin reasserted the notion of the unity of thought and action and partially achieved, in the Russian Revolution, what Marx had predicted. Marx depicted the capitalist stage of societal development as dominated by the bourgeoisie. The chapter also presents an overview of the key concepts discussed in this book.