Sales of Atlas Shrugged soared to 445,000 copies in 2011, more than 50 years after it was published. Books about Rand are proliferating as well, including major biographies by Anne Heller and Jennifer Burns. Is there room for yet another volume in this increasingly crowded field? Marsha Enright has shown that there is.

Ms. Enright promises a lot with her title, Ayn Rand Explained, and she delivers. She brings to her task a background reaching back to the early 1970’s when she first met Rand. Her writing suggests a keen intelligence and an independent spirit. The result is a book that is thorough and careful but not pedantic.

Her personal recollections portray Ayn Rand’s warm and approachable side and not the angry cult figure suggested by some. Particularly charming is the story about the cat jewelry.

A new reader or a moviegoer who wants to learn more about Rand and her philosophy, objectivism, will soon discover that there are two camps of followers. David Kelley’s Atlas Society promotes the view that objectivism, as a set of ideas, is necessarily open to extension by any serious thinker who accepts its basic premises. The Ayn Rand Institute is a far larger group because it receives royalties on the heft sales of Rand’s books. The ARI calls objectivism a closed system. Ms. Enright addresses this conflict head-on, explaining both positions evenhandedly and giving credit where credit is due.

Careful analyses of Rand’s novels are followed by a 40-page explication of objectivism, proceeding systematically, as Rand did, from metaphysics to epistemology to ethics to politics and esthetics. Some readers may find this section heavy going and may want to skip it and return later. If they do return, they should be well rewarded.

A separate chapter on politics takes up the uneasy relationship between libertarians and objectivists. She offers back-to-back sections outlining the case for the “plaintiff” (objectivism) and for the “defendant” (libertarianism). I found these sections particularly interesting now that ARI is making nice to libertarians, a sin that earlier got David Kelley kicked out of ARI.

I thought Nathaniel Branden deserved a little more sympathy than he got in this book. He and Barbara Branden have been the victims of vicious smears from the orthodox camp. Nathaniel has admitted the errors he made in his relationship with Rand while Rand never admitted hers, which were far greater. He has redeemed himself many times over, in my view, by the positive difference he has made in the lives of a great many people, both in person and through his books and lectures.

“Ayn Rand Explained” will be my top recommendation to anyone who asks me about Rand and objectivism.