The last three chapters endeavoured to highlight how the evolutionary pattern innovation/standardization, first applied to mental phenomena, was carried over into Marshall’s economic and social thought. The dialectics of change and adaptation shaped his theory of knowledge, his ethics and even such apparently unrelated concepts as equilibrium and the ceteris paribus. It also inspired his opinions on industrial, social and political issues, guiding his exploration of the way in which various industrial and social systems evolve and their points of strength and weakness. But, while the analytical core of book V and related methodological issues tend to veil the main drift of Marshall’s thought and to divert the reader’s attention to controversial themes, his industrial economics makes his message crystal clear. This could explain why the ‘true’Marshall is invisible to those who search for his identity in his methodological views but is easily detected by those who are mainly interested in his industrial economics. Thus, centring his analysis on the mechanics versus biology controversy, Hodgson comes to the conclusion that Marshall was unable to put economics on the right track because of his endorsement of Spencerian evolutionism and failure to understand the radical novelty of Darwin’s work.1 By contrast, focusing on issues of industrial organization and division of labour, which lay deeper in Marshall’s thought, Becattini and Loasby2 are favourably struck by his emphasis on the twofold, complementary trend of differentiation and integration. These two authors maintain that Marshall’s unorthodox economics was not destined to be overtaken by neoclassical thought because of internal inconsistencies, as Hodgson claims: rather, it opened up new routes of investigation that were lost by Marshall’s successors, unable to follow what promised to be a different trend of economic thought, that has only recently been rediscovered by industrial economists. Industry and Trade is sometimes considered a stillborn work, published when the industrial system had already diverged from that described in the book. However, perceptive readers did not fail to notice the presence of ideas which stand the test of time (Williams 1986: 228). Our interpretation aims to convey the notion that such ideas, far from being brilliant asides of a keen observer of the economic world, form part of a well-structured evolutionary theory. Marshall’s description of industrial phenomena is clearly outdated, but his reasoning is capable of ever new applications.