The curriculum vitae of Prof. Philip V. Tobias. He delivered the Sir Arnold Theiler Memorial Lecture during Faculty Day, University of Pretoria, Faculty of Veterinary Science on the 27th September 1996 at Onderstepoort, South Africa. An article with a similar title appeared in The Proceedings of the American Philosophical Society, Vol. 140, No. 1. (Mar., 1996), pp. 49-64. Click on the link to view the full text article. Access may be restricted to affiliated members of JSTOR.