This book received its original impetus from two seemingly unrelated personal prejudices with which I found myself burdened in the late 1970s. First, the basic science of ecology seemed to be suffering from a lack of solid empiricism, its major tenets stemming from a combination of theory and speculation based on observed natural patterns. Second, the applied science of intercropping appeared to be void of a systematic theoretical framework within which the voluminous and usually empirical work might be interpreted. It seemed logical that the empiricism of intercropping might be usefully put to the service of ecology, whereas the theory of ecology might similarly form the basis of a framework for intercropping.

That ecology appeared to me as an overly speculative discipline may be little more than a reflection of Mario Bunge's observation that sciences tend to oscillate between periods of excessive observation – experimentation and excessive theory – speculation. During the 1940s, 1950s, and early 1960s the field of ecology seemed to be caught in a rather dull phase of observation and data collection. In the late 1960s ecologists discovered probabilities, matrices, and differential equations, and initiated a rich phase of theory development. In the 1980s a great deal of concern seems to be developing over the lack of a solid empirical base to the theoretical explosion, perhaps a new swing of the pendulum.

While it is certainly not true that all ecology is done in an empirical void, most ecologists would probably be forced to agree that theory and speculation have come out of balance with data.