I know not what the world thinks of me, but as for myself, I seem to be only a boy playing on the seashore, now and again finding a smoother stone or a more beautiful shell—all the while the great ocean of truth lies undiscovered before me.

—Sir Isaac Newton (1642-1727)

The story of the quantum is a confused and groping search for knowledge conducted by scientists of many lands on a front far wider than the world of physics had ever seen before—illuminated by flashes of insight, aided by accidents and guesses, and enlivened by coincidences that one would only expect to find in works of fiction.  It is the story of turbulent revolution—of the undermining of a complacent physics that had long ruled a limited domain, of a subsequent interregnum predestined for its own destruction by its inherent contradictions, and of the tempestuous emergence of a much more chastened regime—quantum theory.  And while quantum theory rules newly discovered land with a firm hand, its victory is not complete.  What looks like mere scratches on the brilliant surface of its domain reveal themselves as fascinating crevasses betraying the darkness within and luring the intrepid on to new adventure.  Nor does quantum theory hold undisputed sway but must share dominion with that other rebel sibling—relativity.  And although together these two bodies have led to the most penetrating advances in the search for knowledge—they must remain enemies.  Their fundamental disagreement will not be resolved until both are subdued by a still more powerful theory that will sweep away our present painfully won fancies concerning such things as space, time, matter, radiation and causality.  The nature of this theory may only be surmised—but it will ultimately come down to the very same certainty as to whether our civilization as a whole survives—no more no less.

—Introductory paragraph from The Strange Story of the Quantum (1947) by Banesh Hoffmann.

In the evolution of scientific thought, one fact has become impressively clear—that there is no mystery of the physical world which does not point to a mystery beyond itself.  All highroads of the intellect, all byways of theory and conjecture lead ultimately to an abyss that human ingenuity can never span.  For man is enchained by the very condition of his Being, his finiteness and his involvement in nature.  The further he extends his horizons, the more vividly he recognizes the fact that, as the physicist Niels Bohr put it, we are both spectators and actors in the great drama of existence.  Man is thus his own greatest mystery.  He does not understand the vast veiled universe into which he has been cast for the reason that he does not understand himself.  He comprehends little of his organic process and even less of his unique capacity to perceive the world about him in his rationality and his dreams.  Least of all does he understand his noblest and most mysterious faculty—the ability to transcend himself by perceiving himself in the act of perception.  Man’s inescapable impasse is that he himself is part of the world that he seeks to explore—his body and proud brain are but mosaics of the same elemental particles that compose the dark, drifting clouds of interstellar space.  Man is, in the final analysis, merely an ephemeral confirmation of the primordial spacetime field.  Standing midway between macrocosm and microcosm, he finds barriers on every side and can perhaps but marvel, as Saint Paul did nineteen hundred years ago in saying that the world was created by the word of God so that what is seen is composed of things which do not appear.

—Concluding paragraph from The Universe and Dr. Einstein (1948) by Lincoln Barnett.

If we do discover a complete theory of everything it should be understandable by everyone and not just a few scientists.  Then we shall all, philosophers, scientists and ordinary people, be able to take part in discussing questions as to why both we and the universe exist.  If we find the answer to that it would be the ultimate triumph of human reason—for then we would at last know the mind of God.

—Concluding paragraph from A Brief History of Time (1996) by Stephen Hawking.

The final theory of everything will undoubtedly be a mathematical system of uncommon tidiness and rigor that accommodates the physical facts of the universe as we know it.  The mathematical neatness will arrive first followed by its explanatory power.  Perhaps one day physicists will find a theory of such compelling beauty that its truth cannot be denied—truth will be beauty and beauty will be truth.  The theory will be, in precise terms, a myth.  A myth is a story that makes sense on its own terms, offers explanations of everything we see before us, but can neither be disproved nor tested.  This theory of everything will indeed spell the end of physics.  It will be the end not because physics has been able to explain everything, but because physics has at last reached the end of all the things for which it has the power to explain.

—Concluding paragraph from The End of Physics (1993) by David Lindley.

The theory of one brings the reader face to face with the stunning realization that the universe is bounded—rather than unbounded, as Einstein and others have asserted.  The theory of one delivers the ocean.  It is the theory that spells the end of physics.  It is the monolith of 2001—a spacetime odyssey.