The historian of science cannot be unmindful of the fact that, for better or for worse, science, as practiced now and in the past, furnishes one of our central models of rational thought and judgment. Some would use history to demonstrate the worthiness of science as a model for rationality; others would use history to demonstrate the limitations of science in this respect. Above all, however, awareness of the paradigmatic role of science urges the historian of science to seriousness of purpose in trying to delineate and understand the practice of science in the past. In particular, I here endeavor to delineate and understand, in historical context, James Clerk Maxwell's seminal work in electromagnetic theory. Understanding of matters of any significance, however, seems never to come easily: This book has been long in gestation, and it makes some demands of its reader.

I was introduced to the historical study of Maxwell by Martin Klein, whose work and counsel have been seminal for me.

Jed Buchwald, Francis Everitt, Peter Harman, John Heilbron, Ole Knudsen, and David Wilson have furnished ideas, sources, and encouragement beyond what scholarly citations can acknowledge.

My work has been enriched by the conversation as well as the scholarly publications of Joan Bromberg, Geoffrey Cantor, Alan Chalmers, Michael Crowe, Gregory Good, John Hendry, Jonathan Hodge, Robert Kargon, Donald Moyer, Richard Olson, Paul Theerman, and Norton Wise.