at the University of Virginia was intended to provide a fundamental approach to the description of the circulation from the per­ spective of microvascular mechanics and to examine new methodology that may advance this effort. This book arose out ofthe work presented at the symposium. Aristotle expressed well the need to pursue the causes of a phenomenon in order to achieve a truthful understanding of its nature. In this spirit has each of the quantitative sciences progressed, and in this spirit we hope that this book will provide some understanding of the microvascular events and bio­ mechanical mechanisms underlying the behavior of circulation in general, and of pulmonary and skeletal muscle microcirculation in particular. The integrated treatment of pulmonary and systemic microcirculation provided here is intended to encourage the cross- fertilization of these two research fields.