The problem of the ineffable haunts Blaise Pascal. Whether in his fragmentary Pensées, his personal correspondence, or his scientific writings on the void and geometry, the Baroque thinker gravitates to the same elusive questions - How can reason understand that which surpasses reason? How to speak of that which is beyond words? His seemingly paradoxical inquiry into God's transcendent nature - and its mathematical corollary, infinity - does not dead-end at a logical impasse. This book shows how Pascal overcomes the limits of reason by adopting dissonant cognitive strategies akin to the mystical tradition known as apophatic ('negative') theology. Current scholarship has largely overlooked the presence of apophatic thought in Pascal's work. What emerges from this book is a philosophical dialogue between Pascal and Pseudo-Dionysius, the fifth-century writer of seminal apophatic treatises.