While some of Thomas Eakins's portraits incorporated objects that identified what his sitters did, portrait heads emphasized who they were, as thinking and feeling human beings. Eakins probably perceived William Woolsey Johnson, a professor of mathematics at the US Naval Academy in Annapolis, Maryland, as a kindred spirit, as he once observed, “All the sciences are done in a simple way; in mathematics the complicated things are reduced to simple things. So it is in painting.”