Between 900 bc and 100 bc the inhabitants of classical Greece wrote speeches, verse and books, and travelled about the Mediterranean exporting oil and wine in large earthenware jars. Both activities have been studied in sufficient detail by classicists and archaeologists to enable a psychologist specialising in human motivation to link the rise and fall of Greek fortunes to the ambitions of Greeks of each period, which ambitions in turn were shaped by what they read. During those eight centuries Ancient Greek civilisation developed to a peak in the Golden Age of 475 to 362 bc, then declined. The area of the Mediterranean to which Greek oil and wine jars were exported, to be discovered and dated by modern archaeologists, similarly grew to a peak in the fifth century bc, then declined, as Roman influence increased. Themes of winning or doing well, concern for success, or unique achievements (such as inventing the sailing ship) were coded from six selected classes of writing, including funeral orations, war speeches, and books on farm management. Such themes were most frequent in the period of growth, and thereafter declined steadily through the Golden Age and the period of decline. Placing the two measures on a common timescale (Figure 8.1) McClelland (1961) concluded that achievement themes in Greek literature preceded and, in part, caused the changes in exports. The emphasis on achievement in the writings of the early period produced generations of Greeks who traded further and further afield. But while the Greeks of the fifth century were selling wine and oil over an area of 3.4 million square miles, Greek youth back home were reading literature with fewer mentions of achievement, which was to cause them and future generations to go into the decline of 362 to 100 bc. The lag is significant, for it suggests cause and effect. A simple positive correlation between literary themes and exports would not prove much, for spurious correlations, based on general economic climate, are notoriously easy to demonstrate.