Human beings have the ability to convert complex phenomena into a one-dimensional sequence of letters and put it down in writing. In this process, keywords serve to convey the content of the text. How letters and words correlate with the subject of a text is something Eduardo Altmann and his colleagues from the Max Planck Institute for the Physics of Complex Systems have studied with the help of statistical methods. They discovered that what denotes keywords is not the fact that they appear very frequently in a given text. It is that they are found in greater numbers only at certain points in the text. They also discovered that relationships exist between sections of text which are distant from each other, in the sense that they preferentially use the same words and letters.