▁book ▁exam ines ▁four ▁major ▁domains ▁of ▁thought ▁via ▁fundamental ▁think ers : ▁ ▁Adam ▁Smith ▁in ▁economic ▁freedom ; ▁Dar win ▁in ▁bi ology ; ▁Thomas ▁Jefferson ▁and ▁Alexander ▁Hamilton ▁in ▁dem ocr atic ▁government ; ▁and ▁Karl ▁Marx ▁in ▁human ▁equality . ▁The ▁treatment ▁includes ▁trac ing ▁the ▁history ▁of ▁how ▁these ▁expanded ▁in ▁influence ▁through ▁the ▁ 1 9 th ▁and ▁ 2 0 th ▁century , ▁exam ining ▁their ▁diverse ▁impact s ▁up ▁to ▁the ▁present ▁time . ▁The ▁authors ' ▁key ▁point ▁is ▁that ▁ideas ▁like ▁dem ocr atic ▁freedom ▁and ▁economic ▁liberty ▁are ▁no ▁less ▁alive ▁and ▁fought ▁over ▁today ▁than ▁ 2 0 0 ▁years ▁ago , ▁and ▁this ▁will ▁not ▁stop . ▁Need less ▁to ▁say , ▁this ▁is ▁no ▁less ▁true ▁for ▁Dar win ▁and ▁for ▁Marx . ▁As ▁Zak aria ▁notes , ▁" For ▁almost ▁a ▁century , ▁hundreds ▁of ▁millions ▁studied ▁[ Mar x ' s ] ▁work ▁as ▁g ospel . ▁Power ful ▁nations ▁like ▁the ▁Soviet ▁Union ▁and ▁Ma o ist ▁China ▁organized ▁themselves ▁around ▁his ▁theories . ▁In ▁most ▁other ▁soci eties , ▁politics ▁were ▁defined ▁and ▁organized ▁in ▁opposition ▁to ▁his ▁views ." ▁ ▁After ▁their ▁chap ters ▁on ▁these ▁think ers , ▁the ▁authors ▁turn ▁to ▁re actions ▁against ▁them , ▁in ▁the ▁form ▁of ▁religious ▁fund ament alis ms ▁( Christ ian ity ▁and ▁Islam ), ▁total itar ian ism , ▁fasc ism , ▁and ▁forms ▁of ▁reaction ary ▁re jection . ▁A ▁powerful ▁argument ▁is