Time like space, can be divided up. Our problem now is how use such divisions to locate and understand the world- economies. It is not an easy task, for in their slow historical progress they admit only approximate dates: a period of growth can be dated to somewhere between ten and twenty years and not always then; a change in centre of gravity might take more than a century: Bombay, ceded to the English by the Portuguese government in 1665, had to wait a hundred years before it supplanted the trading city of Surat around which the economic activity of the whole of western India had previously been organized.  So we are dealing with history in slow motion, with journeys that seem never-ending and so lacking in revealing incidents that there is a risk of inaccuracy in reconstructing their routes. These power centres seem suspended in time: the history takes centuries to build or destroy them.

Geographical space as a source of explanation affects all historical realities, all spatially- defined phenomena: states, societies, cultures and economies. Cultures are ways of ordering space just as economies are.  Depending which of these 'sets' we choose, the significance and role of space will be modified accordingly.. For example, the world economy is an expression applied to the whole world. It corresponds to 'the market of the universe', to 'the human race, or that part of the human race which is engaged in trade, and which today in a sense makes up a single market'.

A world-economy only concerns a fragment of the world, an economically autonomous section of the planet able to provide for most of its own needs, a section to which its internal links and exchanges give a certain cultural unity. For instance, the Mediterranean in the sixteenth century was a world-theatre or world- economy - meaning by this not merely the sea itself but the whole area stimulated by its trading activities, whether near its shores or far away. The Mediterranean region, although divided politically, culturally and indeed socially, can effectively be said to have had a certain economic unity, one imposed upon it from above on the initiative of the dominant cities of northern Italy, Venice foremost among them, but also Milan, Genoa and Florence.

We can in fact trace a relatively smooth succession of economic stages through the Middle Ages.

In the later Roman Empire, both peasants and slaves increasingly became coloni on large estates or villas owned by a powerful upper class, who would offer them protection in return for the payment of taxes and so on. The same pattern was repeated in the early Middle Ages under the Frankish kings, especially Charlemagne, when the possession of lands (together with the peasants who happened to be working the land) was granted to the nobility in return for service. The peasants became 'serfs', and so bound in law to work for the local lord in return for his patronage and protection. They were not, however (at least not usually) 'slaves': many had their own plot of land, and lived under laws administered by the local manorial court.

Serfdom was the basis for the development of feudalism, the crucial added element in which was the evolution of the earlier barbarian warrior, under the influence of Christianity, into the armoured knight.  The word feudalism derives from the Latin feudum, meaning fief. This class of knights was the backbone of the new nobility. The Frankish- German code of honour and personal fellowship became codified into an elabourate hierarchy of relationships of loyalty, defined by oath- taking and the grants of land and privileges. In many ways this code of chivalry was more effective in holding the fabric of society together than any written set of laws could ever have been. On the land, an emphasis on arable farming by means of crop rotation (the three-field system) led to the growth of communal or cooperative agriculture in and around the villages - villages sheltered by and economically supportive of the local castle.

The next stage in economic and social development was to be the gradual evolution of these feudal fiefs, which were entirely at the disposal of the nobility, into territorial states. This happened by a process of conquest, amalgamation, and the consolidation and extension of privileges among the nobility which had now become hereditary. The population explosion and the growth of long-distance trade, caused the castles and villages of early medieval times to expand into walled cities by the eleventh and twelfth centuries. Outside the city walls, the peasant farmer of these times possessed a great measure of independence, being protected by the Church, by strong bonds of community and by local custom. The monasteries played their part too, both as employers and landowners, and as places of refuge for the poor.

Towns and guilds were one of the most important fruits of Christian inspiration. In the new towns of this period, according to Ernst Troeltsch,

Each city was partly governed by a system of craft and trade guilds, under the patronage of some popular saint. These controlled the quality, price and distribution of goods, as well as looking after the education, employment and social welfare of craftsmen. Russell Sparkes says,

This principle of voluntary association under religious protection was the basis, in fact, for the new forms of municipal government that took shape all over Europe during this time, culminating in the commune, where the inhabitants got together and bound themselves by oath to keep the common peace and to defend common liberties. Italy in particular became in this way a land of city states. At various times the nobles - who continued their military feuding - were actually driven out of the cities altogether. Linked to the rise of the merchant classes (of whom St Francis of Assisi, was a member), the city states were to be the basis for the next phase of civilization.

It was about fifty years ago that the social sciences made the discovery that human life was subject to fluctuations and swings of periodic movements, which carry on in endless succession. Such movements, harmonious or discordant, bring to mind the vibrating cords or sounding-boards of schoolday physics. G.H. Bousquet for instance wrote in 1923;

'The different aspects of social movement [have] an undulating rhythmic profile, not one that is invariable or varies regularly, but one marked by periods when [their] intensity increases or diminishes'.

'Social movement' can be taken to refer to all the movements at work in a given society, the combination of movements which forms the conjuncture or rather the conjunctures. For there may be different conjunctural rhythms affecting the economy, political life, demography and indeed collective attitudes, preoccupations, crime, the different schools of art or literature, even fashion (although fashion in dress changes so quickly in the West that it is more a question of the day-to-day than the conjunctural). Of all these, only the economic conjuncture has been seriously studied, if not pursued to its logical conclusion. So conjunctural history is extremely complex and by no means complete.

Many historians identify the cultural power cycles of capitalism with the cataclysmic explosion of the industrial revolution. But even in this 'short-term' perspective, we are talking about three or five centuries, and therefore about a long-lived structure - which is not the same thing as an absolutely unchanging reality. The long- term is made up of a succession of repeated movements, with variations and revivals, periods of decline, adaptation or stagnation - what sociologists would describe as structuration, destructuration and restructuration. Sometimes too there are major breaks with the past -and the industrial revolution was certainly one such. It seems that it is in the nature of capitalism, a sort of rule of the game, that it thrives on change, drawing strength from it, being ready at any moment to expand or contract itself to the dimensions of the all-enveloping context which, as we have seen, limits in every period the possibilities of the human power bases everywhere in the world.