In journalism, there is an old saying, "Follow the money." This is a proven method of tracking malfeasance in politics.
I have found that in writing biographies, following the money is important in a different way. Keeping track of how much my subject has made from her work and what she has spent on significant purchases helps to determine the relative smoothness or bumpiness of her life.
A biography, as opposed to a literary study or an artist's monograph, is about the whole of the person's life, not just The Work. Biographers are concerned with how our subjects lived, which means researching and writing about personal matters, including the ancillary aspects of a career that depended on favorable treatment from publishers or galleries.
Few of us are able to conduct our lives without worrying about money, and the people I write about were no different. Financial concerns weighed heavily on them, at times distracting them from their work.
Describing money issues, along my subjects' health, leisure pursuits, relationships, appearance, tastes in clothing and furnishings, and daily irritations and pleasures, makes the people I write about come alive as human beings. They may be towering figures in their fields, but in other ways they are not so very different from us. And it is on that basis that we can best appreciate how they soared above their difficulties to make the work we revere.