The important contribution to agricultural science by A.D. Thaer and J.H.v. Thünen is not a question that needs to be argued. This paper aims not only to survey the historical studies of these classics using quite new information after the reunion of the two Germanies, but also to discuss the current interpretations in view of sustainable agriculture by these classical models as a blueprint of the future. The author could find some aspects of analytical tools from these models to construct a methodology of agroecology, that is to say, an optimization of ecology and economy in agriculture. It would be also possible to develop the theory of agroecology on the basis of these classical studies.