A poet, a physicist, and a philosopher explored the greatest enigmas of the universe – the nature of free will, the strange texture of reality, the true limits of the mind – and each revealed, in their own way, an enlightening, universal existential truth.

The young Argentine poet Jorge Luis Borges was madly in love, and the sudden breakup literally caused him to collapse. However, it was this very collapse that also made him realize an irrefutable truth: that love is inextricably intertwined with loss.

The German physicist Werner Heisenberg was battling the scientific establishment over the concept of absurdity in the quantum world when he experienced his own revelation: a complete and fully accurate description of reality is utterly unattainable.

The Prussian philosopher Immanuel Kant thoroughly explored the axiomatic assumptions of the rational mind and transformed the vertigo of his conclusions into the culmination of a grand philosophical system, the idea that the human mind has fundamental limits and that, thanks to these limits, we both flourish and err.

The works of Borges, Heisenberg, and Kant, through literature, science, and philosophy respectively, converge around this common, evocative, and unsettling truth: that there is an unbridgeable gap between the reality "out there" and the reality as we experience it. From this profound truth springs forth a plethora of pivotal ideas: concepts such as the self, free will, and the purpose of human life, the principles of ethics, aesthetics, and logic, the origins and nature of the universe itself.

This book, studying together the lives and works of these three great minds of the twentieth century, repeatedly highlights how our existential questions, the great mysteries surrounding humanity's place in this world, will likely hover unanswered forever over mankind, not as a threat, but as a reminder of the humility of human nature.

"Fascinating!" -Carlo Rovelli

"Physicists explain reality, poets crystallize our emotional response to it, and philosophers systematize mental connections. All these endeavors are plagued by uncertainty. Heisenberg, Borges, and Kant struggled with this uncertainty throughout their lives. Eglinton offers us a highly enlightening tour of the captivating labyrinth of their spiritual cross-relations." -Mario Livio, author of The Golden Ratio

"A book of astonishing intelligence and beauty. William Eglinton explains the paradoxes of physics, metaphysics, and literature, showing how they shape the boundaries of the visible world and the possibilities of the invisible, reminding us that the humanities at their best unite art with science in the diligent quest for truth." -Merve Emre, Professor of Creative Writing at Wesleyan University, columnist for The New Yorker

"We humans are ambitious; we want to be able to know everything. Yet the universe continuously presents us with obstacles, imposing limitations on our knowledge and rendering our relationship with the truth inevitably indirect. Eglinton ingeniously relates Borges, Kant, and Heisenberg, three of the boldest explorers of the limits of knowledge, ultimately inspiring our admiration for our ability to perceive so much from an elusive reality." -Sean Carroll, author of The Biggest Ideas in the Universe

"A haunting reminder of the perspectives that open up before us so long as we do not forget how amazing beings we are." -John Kaag, author of Hiking with Nietzsche