================= HES POSTING ================= The answer is that Marshall wanted to convey the producers' point of view rather than the consumers'. While it is reasonable to say that decisions to buy depend on price, decisions to produce take the quantities as given and consider the price at which a given quantity can be sold as the true variable. The producer knows his costs of production for any given quantity and has to guess whether the selling price of that quantity will repay his costs of production. Therefore, while demand is a function of price, supply is not (cf. for example Industry and Trade, p. 188, note) (II,i,3). This approach is clearly present in the Early Economic Writings dealing with the theory of value, where the modern use of representing quantities on the horizontal axis and prices on the vertical was introduced (in contrast to what other economists of the period were doing). Of course, for Marshall this is a simplification, since quantity and price are mutually related and we cannot properly say that one dependes on the other. Tiziano Raffaelli [log in to unmask] ============ FOOTER TO HES POSTING ============ For information, send the message "info HES" to [log in to unmask]