The article by Fulde, Thalmeier and Zwicknagl traces many of the recent developments in the field of strongly correlated many electron systems. It is very useful both as a reference and a pedagogical exposition since it places these developments into a historical context beginning with early developments in the electron theory of solids. The second article in this volume, by Bréchet and Hutchinson, concerns pattern formation in metals and alloys. Spontaneous pattern formation is the development of a regularity, either in the spatial distribution of the material in a system or in its development in time, of a lower symmetry than that of its cause. These phenomena have been of considerable interest to the non-linear physics community, in particular in fluid dynamics and in chemical reactions.