I've just finished reading a really amazing biography, beautifully written and wonderfully interesting as well, Jacques Roger's Buffon: A Life in Natural History (translated by Sarah Lucille Bonnefoi). It combines the virtues of the best kind of intellectual biography with the life-story-telling that makes biography so compelling (its pleasures akin to the novel's).
The thing I was most impressed with is the way Roger handles Buffon's vast corpus of writing. It's hard to describe, but Roger serves as Buffon's sympathetic but cool-headed advocate: he quotes at length when he needs to, situates those quotations by means of almost chameleonic paraphrase and yet with a wry turn of phrase of his own can show where Buffon is not being his best self.
Here's a paragraph from the epilogue, in which Roger describes Buffon's death and funeral (bookending the short chapter) and reflects on his life and work in summary:
Of what was he thinking, this dying man who received the last sacraments of his Church? We will never know: the last moments of a human life concern God only. What had he believed during his lifetime? Was he a Christian, a Deist, an atheist? This has been much debated. There are a hundred ways to believe or not believe. Is it legitimate to define a religious thought or sensibility as if it were not primarily the expression of an intellectual temperament? In the same way, is it possible to study a "scholar" or a "writer" as if he were not the same man who thinks, who seeks, who writes? Such examinations are useful, and we have already made them. Here, it is the deep forces of a personality and a temperament that we would like to reach before taking leave of an extraordinary man. This is a riskier attempt, since it entails finding a unity that perhaps did not really exist.
The book of Roger's that I fell in love with a couple years ago was The Life Sciences in Eighteenth-Century French Thought, the word "magisterial" is embarrassing and probably overused but this book really is the dictionary definition of magisterial and so interesting, it was written almost fifty years ago (though only translated into English more recently) and yet it has that freshness and lucidity of thought and style that makes a book feel like it's brand new. It would be a good desert-island read, it would sustain you in conditions of limited stimulus.