In Rebbe: The Life and Teachings of Menachem M. Schneerson, The Most Influential Rabbi in Modern History (Harper Wave, June) Joseph Telushkin (Jewish Literacy) offers admiring but clear-eyed insight into the life and legacy of the 7th Rebbe of the Lubavitch Chabad movement.

Why is the Rebbe still such a presence in the Chasidic world, 20 years after his death?

The best evidence of the legacy the Rebbe left behind him is what has happened since his death, namely, that far from disintegrating at the loss of his charismatic leadership, Chabad has grown and expanded greatly, and is now in 48 states and 80 countries. Part of the reason is that he left behind a collection of teachings that have made the movement self-sustaining. Some of those teachings can be deduced from the Rebbe's behavior, for example, “Anything worth doing is worth doing now.” How many great ideas has almost everyone not followed up on because they were set aside, because we promised ourselves we would do them tomorrow? The Rebbe said rather, "Do it now."

What surprised you the most about his life?

Given the Rebbe’s strong opinions on various matters, it was surprising the degree to which his decisions, as his secretary Rabbi Yehuda Krinsky told me, were not “cookie-cutter." He always tailored his advice to the individual in front of him. For example, because of the secular or anti-religious orientation of many university faculty, he was generally opposed to a college education for his followers. But there were instances in which he approved it, and many instances in which he urged people to finish their degrees. It really depended on the circumstances and the person.

What about the belief among some that the Rebbe was the messiah?

I address this issue in detail in my book, but I can say that the controversy regarding the Rebbe as a messiah or potential messiah is not central at this time to Chabad’s functioning.

How did you gain access to the materials for your research?

Chabad is not secretive; they really want the Rebbe's teachings to get out to a more general readership. Though this was not an authorized biography and Chabad had no editorial control over the book's contents, they nevertheless gave generous access to the people who could give an account of things the Rebbe did or said. I had to work very hard to research this biography; the Rebbe really said very little about himself.

What do you expect the reception will be in the Lubavitcher community?

I believe the book will be viewed positively. It’s not that I agreed with all the Rebbe's views, but I think I’ve nonetheless presented the issues accurately and fairly. I like to say that this is an admiring book, but one that has been written with open eyes.