FM 97-2 Author: G. Gallavotti Title: Atomism, Boltzmann and nonequilibrium statistical mechanics Text of a talk presented at the Symposium "The genesis and development of ethernal thruths", ETH (Wissenschaftphilosophie und Wissenschaftforschung departement f\"ur Humanwissenschaften), Z\"urich, 4 nov 1996. Keywords: Nonequilibrium, Statistical Mechanics, Entropy, Chaos, Science history Fisica, Universita' di Roma La Sapienza, P.le Moro 2, 00185, Roma, Italia. e-mail giovanni@ipparco.roma1.infn.it tel. 6-49914370, fax 6-4957697 Home pages: http://www.math.rutgers.edu/~giovanni