The concept of participation in a transcendent domain of existence is central to the Platonic and the Judaeo-Christian traditions. It is how thinkers throughout history have justified existence itself, explaining temporal being vis-à-vis God. Yet in the wake of secularisation and the widespread phenomenon of disenchantment, this once ubiquitous and coveted notion has fallen into desuetude. The essays in this volume analyse and explore this key concept in the history of Western thought. They provide, for the first time, a rigorous and accessible account of participation, a pivotal concept in Western philosophy and theology, from antiquity to the modern era. Bringing together contributions by an international team of leading scholars of the Platonic tradition, the volume challenges a standard distinction between philosophy and theology. It also enables a comprehensive understanding of figures who do not fit neatly into the modern university's division of these subjects.