Environmental problems, as far as they raise economic questions, even conflicting with pre-ecology economics, can be tackled in different ways. The way chosen by Bernard Coupe was not the French 'voie royale', -a Louis-XIV equivalent of a speedway - but the narrow path, con sisting in carefully implementing a simple but valid model. This model is amenable to many extensions, but it reveals the core of some economic-ecological problems: the search for acceptable solutions when one is confronted with a set of rather narrow constraints. A not uninteresting finding is that 'full-employment' solutions do seem to exist, though leading to different uses of the product made available. How such solutions are to be politically implemented is then a further stage of the reasoning, not taken up in this book. We spent, Bernard and I, many a well-filled hour in discussing the technicalities of the exercise: the consumption and investment functions, with their estimation problems, the treatment of the transportation sector, problems in geometric programming, et de quibusdam aliis. Especially when prefacing the final product, one is particularly pleased to be able to evoke the times past, but well spent. Bernard Coupe will certainly in the course of his development work in Africa, use the spirit and techniques of this approach. We can expect in the future some good reporting on this facet of his work too.