As with nearly all aspects of our Western world, botanical classification began with the ancient Greeks. This chapter discusses the logical contributions from well-known authors such as Socrates, Plato, and Aristotle, all of whom have profoundly influenced logical thought and have had impacts on observations of the plant world and efforts to understand it. Theophrastus was particularly important because of his special interest in plants. Similar developments also took place in China and India. The Romans were practical people, more interested in administration of their vast empire and development of new engineering methods, rather than philosophical concerns. Pliny the Elder was an industrious compiler of information, who helped preserve data about plants in works that no longer exist.