Robert L. Devaney quotes:

Modern dynamical systems theory has a relatively short history. It begins with Poincare (of course)... [to whom] a global understanding of the gross behavior of all solutions of the system was more important than the local behavior of particular, analytically-precise solutions.

It can be argued that the mathematics behind these images [of the orbit diagram for quadratic functions and the Mandelbrot set] is even prettier than the pictures themselves.

It has been said that the three great develpments in twentieth century science are relativity, quantum mechanics, and chaos. That strikes me the same as saying that the three great developments in twentith century engineering are the airplane, the computer, and the pop-top aluminum can. Chaos and fractals are not even twentieth century ideas: chaos was first observed by Poincare and fractals were familiar to Cantor a century ago, although neither man had the computer at his disposal to show the rest of the world the beauty he was seeing.