From Plato's eidos, to Descartes' cogito, to Kant's numenon, our understanding of reality has faltered at a seemingly impossible, double-edged, impasse. First, an ontological 'hard problem': If mind and matter are so radically different and separate, how do they ever interact? Second, a related epistemological conundrum: How is it possible for mind to ever know anything about matter--including whether it even exists? Then came Whitehead. By shifting the mind-matter relation from substances interacting in space to complementary phases in process, he offered a way through, or at least around, the Kantian impasse. His panpsychist ontology came hand-in-glove with an epistemology of intersubjectivity: We can know the objective physical world because the actual world is not just physical, and because it necessarily and intimately informs and constitutes our subjective experience. But is this panpsychism or idealism? And how does it avoid the interaction problem that bedevils dualism or the problem of emergence that embarrasses materialism?