The life of Jan Evangelista Purkinje (1787–1869) has fascinated students from many disciplines. Histologists marvel at his early descriptions of cells, physiologists admire his attempts to relate structure to function, pharmacologists view in awe his heroic experiments on self-administered drugs, forensic scientists acknowledge his role in the use of fingerprints for identification, and Czech patriots salute his awakening of pride in their nation. Yet all these achievements followed his initial enquiries into vision. It is this psychological dimension that fostered our collaboration, because it is the discipline from which we both come. In his doctoral dissertation Purkinje sought to describe a range subjective visual phenomena and to account for them in objective terms. His dissertation was published in German in 1819 and reprinted in 1823. Surprisingly, it has not been translated into English, and it was this situation we wished to remedy.
As the title suggests, the present volume is bifocal. In the narrow sense it refers to Purkinje's studies of vision, but in its broader view it concerns Purkinje's anticipation of neuroscience. We think of neuroscience as a modern discipline, but its origins are ancient. Purkinje provided evidence to support both its cellular and its conceptual base. At the cellular level his acute vision is immortalized within our bodies, with Purkinje cells in the celebellum and Purkinje fibers surrounding the heart. At the conceptual level, he sought to relate subjective phenomena to their