The Internet is generally seen as the starting point for networked information, but scientific and scholarly networks have been in place for centuries.

Mapping those networks, and tracing the criss-crossing and overlapping interactions between scholars, is part of Stanford University's Mapping the Republic of Letters initiative, one of several projects in the worldwide collaboration called The Digital Republic of Letters.

The site provides visual overlays of, say, Isaac Newton's written correspondence with Voltaire in France. The visuals can be tweaked by adding or removing parameters from the visualisation tool. Click on the Charts, Maps, and Tools link to see what is possible. The project aims to explore Correspondence and Intellectual Community in the Early Modern Period (1500-1800) and is based around a number of case studies of individuals such as Benjamin Franklin, Athanasius Kircher, Voltaire, John Locke and of groups such as 'Grand Tour' Travellers.