Two books on John Stuart Mill [by Mrs. Himmelfarb] appeared in 1974. The first was an edition of Mill's On Liberty. The second book, On Liberty and Liberalism: The Case of John Stuart Mill, was an exploration of the "two" Mills - the one who wrote OnLiberty and the one who wrote Mill's other works. There is, Himmelfarb stipulated, a qualitative difference between the writings of the two, the former being strongly influenced by his long-time companion and later wife, Harriet Taylor, and the latter, whom Himmelfarb clearly preferred, belonging "to an older liberal tradition."

Gertrude Himmelfarb was born in Brooklyn, New York, on August 8, 1922, the daughter of Bertha and Max Himmelfarb, a manufacturer. She graduated from New Utrecht High School in Brooklyn in 1939 and attended Brooklyn College, studying history and philosophy. She graduated from Brooklyn College in 1942 and in the same year married Irving Kristol but retained her maiden name for professional purposes. In the late 1990s, one writer wrote: "No family has had a greater impact on today's conservatism than the Kristols, " writes Jacob Weisberg in the New Yorker of [then] editor Bill; his mother, historian Gertrude Himmelfarb; and his father, public philosopher Irving.

The young couple moved to Chicago, where Himmelfarb began graduate work in history at the University of Chicago. Himmelfarb wrote her Master's thesis on Robespierre under the direction of well-known historian Louis Gottschalk and received her MA in 1944. She continued her graduate studies while Kristol served with the U.S. Army. After Kristol's discharge in 1946, they went to England, where Himmelfarb had been awarded a fellowship to Girton College, Cambridge University. At Cambridge she continued her doctoral research on Lord Acton, a fascinating and paradoxical Victorian figure, both European and English, a political thinker and historian.