This is a review of Graham Farmelo's biography of P.A.M. Dirac. As far as I know, this is the only one (please let me know if you are aware of another such biography).
From just reading the review, it does seems that Dirac is a rather quiet and eccentric person. Still, I found an interesting passage that may be attributed to him that's written in this review:
For his part, he insisted that the quantum world could not be expressed in words or imagined. To draw its picture would be “like a blind man sensing a snowflake. One touch and it's gone”. Its beauty revealed itself only in mathematical formulae.
Kewl! I hope this is truly his sentiment, and not simply a conclusion made either by the reviewer or the biographer. This is because this is similar to my argument when I wrote "Why is QM So Difficult?", and why, the mathematical formulation of QM IS QM, whereas the conceptual aspect of QM is rather secondary.
I suppose I have to get the book and check it myself.