The socialist philosopher and economist Karl Marx is considered one of the most important and influential thinkers of modern history. Marx was a strong believer in social and economical progress and he connected those characteristics with ethnic and racial groups. For Marx, social characteristics were inherited in Lamarckian fashion and he feared proletarian would hereditarily transform into a "degenerate race" due to working conditions. In Marx and Engels' theory some "races" were endowed with certain innate characteristics which enabled their progress towards Communism while others were considered incapable of reaching that historical stage. Marx showed special antagonism towards the slavs which he considered inherently reactionary. Despite being of Jewish ethnicity, Marx understood the Jewish people as religiously tied to capitalism. Marx considered Mexicans "lazy", and commemorated the conquest of California by the United States.