A successful neurosurgeon, who has taught at Harvard Medical School and other universities, spent his life dismissing claims of heavenly out-of-body experiences and refuting such talk with scientific logic, until he himself had a near-death experience.

During that time, Dr. Eben Alexander says he saw heaven and knows the afterlife exists. Now he's telling the world in his new book, "Proof of Heaven."

Alexander's tale is the cover story on Newsweek's latest issue, which features the headline, "Heaven Is Real: A Doctor's Experience Of The Afterlife." Alexander, a Christian, claims he took the journey to the afterlife when he slipped into a coma in 2008 after contracting a very rare bacterial meningitis.

Click here to read Dr. Eben Alexander's full account via the Daily Beast.

Alexander describes the heaven he saw over the course of seven days in a coma in an article for the Daily Beast, a Newsweek affiliate:

Toward the beginning of my adventure, I was in a place of clouds. Big, puffy, pink-white ones that showed up sharply against the deep blue-black sky.

Higher than the clouds—immeasurably higher—flocks of transparent, shimmering beings arced across the sky, leaving long, streamerlike lines behind them.

Birds? Angels? These words registered later, when I was writing down my recollections. But neither of these words do justice to the beings themselves, which were quite simply different from anything I have known on this planet. They were more advanced. Higher forms.

A sound, huge and booming like a glorious chant, came down from above, and I wondered if the winged beings were producing it. Again, thinking about it later, it occurred to me that the joy of these creatures, as they soared along, was such that they had to make this noise—that if the joy didn’t come out of them this way then they would simply not otherwise be able to contain it. The sound was palpable and almost material, like a rain that you can feel on your skin but doesn’t get you wet.

Alexander says that he traveled through this heaven, surrounded by "millions of butterflies," with a woman. This woman gave him three messages: “You are loved and cherished, dearly, forever," “You have nothing to fear" and “There is nothing you can do wrong.”

Eventually, the neurosurgeon awoke from the coma. He penned a book, "Proof of Heaven," describing his journey. The book is due out Oct. 23.

"Dr. Eben Alexander's near-death experience is the most astounding I have heard in more than four decades of studying this phenomenon," reads a review from Raymond Moody, M.D., Ph.D., author of "Life Beyond Life." He goes on to say that the "circumstances of [Eben's] illness and his impeccable credentials make it very hard to formulate a mundane explanation for his case."

"I stood at Eben’s bedside ready to read Last Rites," writes Rev. Michael R. Sullivan, Rector, Holy Innocent’s Episcopal Church in Atlanta, Ga. "With vivid detail and description, he invites you to walk with him to that place none of us has experienced yet in our humanity we know we shall one day certainly travel. Having survived a near death experience and brought his neurological expertise and background to it, we gain both the insight of the mystics in his poetic words and the reality of the physical world in his scientific explorations."

Still, some remain skeptical. Gawker published a piece comparing Alexander's story to "Experiences" essays written on Erowid.org -- a site a featuring a collection of writings from conscious drug users about their experimentations and trips.

(Photo via Flickr user Jamie Pachomski)