The aim of this paper is to ponder upon Marshall’s conception of equilibrium and to confront it withWalras’s. In a first section, I present a rational reconstruction of the Marshallian conception. In contrast to its standard tripartite classification interpretation, I claim that this conception is based on two interlinked equilibrium concepts, normal equilibrium and market equilibrium. Several features are brought out : (a) this conception is based on what I call the ‘period of analysis’ hypothesis; (b) in this conception disequilibrium states have an effective; (c) the notion of long period equilirium then turns out to have a most elusive meaning; In a second section, I compare Marshall and Walras on equilibrium and time. Whenever the comparison bears on their production models, a sharp contrast emerges in particular with regard to the meaning and possibility of disequilibrim. When Walras credit model is taken into account the result is more complicated. An important difference is still present which can be traced back to the fact that when it comes to time the Marshallian appproach privileges the duration aspect while dodging the irreversibility or arrow of time aspect while the contrary is true for the Walrasian approach.
