Friedrich Horner, whose name is associated with the clinical syndrome that follows unilateral interruption of the cervical sympathetic fibers, was born in Zurich, where his father was a practicing physician.1 Horner, delicate of body but strong of mind, was schooled in the classics, mathematics, and natural history. Upon completion of his country's compulsory military training in 1849, he matriculated in the University of Zurich and went on into medicine; there he gained high scholastic honors, particularly in anatomy and physiology under Carl Ludwig and in botany under Oswald Heer. Sorrow came to the family during this time, and within a few months his parents and brother died of unrelated conditions. He received the MD degree in 1854, presenting a thesis on the curvature of the spine. His postgraduate work was begun in Vienna where he took courses with Oppolzer, Skoda, and Hebra. This was followed by an assistantship under Graefe,