Concentration of measures:
Talagrand's "work illustrates the idea that the interplay of many random events can, counter-intuitively, lead to outcomes that are more predictable, and gives estimates for the extent to which the uncertainty is reigned in."
There are literally hundreds of #proofs of #Pythagorus’ #Theorem and this book has about three hundred of them. It was published in the 1920s but my copy was printed to order and bound in #India. I hope it will be both a reference and a talking point.