There are some words that mathematicians use a lot, and to suggest things that are similar but not identical. “Normal” is one of them. Distribution is another, and in the End 2016 A-to-Z I discussed statistical distributions. To look at how a process affects a distribution, rather than a particular value, is one of the great breakthroughs of 19th century mathematical physics. This has implications about what it means to understand and to predict the behavior of a system.