The ascent to the One - this is the center of Plotinus' philosophy and the Neoplatonism that stems from it. The fact that such an ascent to the One also plays a central role in Plato's work is one of the most important insights of recent Platonic research. This book draws the consequence from this and redefines the relationship between Plato and Neoplatonism. It combines the first comprehensive presentation of Plotinus' theory of the Absolute with a reconstruction of Plato's henology. In doing so, it highlights the close connection between the two and simultaneously underscores the enduring philosophical relevance of the topic.