By this point, basic facts are dependable. Dates of birth and death are rarely a problem, since local governments kept good records. There are also government and personal records of much else a man's life - his salary, his military record, his jobs, his taxes, his hotel bills, his divorce suit ... But these are again not the point. Among the men on the chart on the previous page, only Gauss was important for non-mathematical reasons. For the others, what is most important is to explain where a person's mathematics fits into the main stream of mathematics - not just bald facts, but real intellectual explanation.

This is not to say that biographical matters should be ignored, but they are not usually the most important things to say about most mathematicians.