This issue of Parabola incorporating Function features two articles on the history of mathematics. The first of these tells the recent history (only a little more than three hundred years ago) of Newton and Leibniz' calculus and the second article tells the much earlier history (more than two thousand five hundred years ago) of the mathematics of Pythagoras and of his (likely) wife Theano.
I found both articles fascinating. Once we have new mathematical knowledge it is difficult to properly imagine a time without it. As an applied mathematician I find it particularly difficult to imagine a world without calculus. Among other things calculus provides us with tools to predict the future. Halley's prediction (with refinements by Clairaut) that a comet observed in 1682 would reappear over the Earth in 1758 is a wonderful early example of the merits of this approach.