Introduction

This introduction discusses historical topics of personal interest. The topics chosen are not in any way comprehensive, nor motivated by anything other than models, theories, and experiments that I found particularly enlightening. The reader is enthusiastically referred to the many existing articles and books that also give introductions to granular materials, particularly in areas with which I am less familiar (e.g., engineering, for which readers are referred to the extensive literature, e.g., [15,25]). The personal retrospective gives an emphasis to simple statistical explanations, an aesthetic property that has proven exceptionally useful for my own study of granular materials. The section concludes with a review of my personal area of research: geometrically cohesive materials.