We cannot live by reason alone. This is why no quantity of reason, applied as antiseptic, can compete with the balm of faith, once the terrors of this world begin to intrude upon our lives. Your child has died, or your wife has acquired a horrible illness that no doctor can cure, or your own body has suddenly begun striding toward the grave—and reason, no matter how broad its compass, will begin to smell distinctly of formaldehyde. This has led many of us to conclude, wrongly, that human beings have needs that only faith in certain fantastical ideas can fulfil. It is nowhere written, however, that human beings must be irrational, or live in a perpetual state of siege, to enjoy an abiding sense of the sacred. On the contrary, I hope to show that spirituality can be—indeed, must be—deeply rational, even as it elucidates the limits of reason. Seeing this, we can begin to divest ourselves of many of the reasons we currently have to kill one another.

Science will not remain mute on spiritual and ethical questions for long. Even now, we can see the first stirrings among psychologists and neuroscientists of what may one day become a genuinely rational approach to these matters—one that will bring even the most rarefied mystical experience within the purview of open, scientific inquiry. It is time we realized that we need not be unreasonable to suffuse our lives with love, compassion, ecstasy, and awe; nor must we renounce all forms of spirituality or mysticism to be on good terms with reason.

Sam Harris, The End of Fair: Religion, Terror, and the Future of Reason, London, 2005, p. 43