Once while an undergrad, I took an autumn off to teach English in China. Packing light, the only book I brought with me was the unabridged Don Quixote, figuring that a solid 1,000 page tome would be more than enough to last my entire stay.
I finished it in six weeks.
At first, this wasn’t a big deal, for I was kept more than busy by teaching middle schoolers, watching pirated DVDs, and most of all exploring the massively complex land of China.
But then, around late-November/December of that semester, something odd happened: I became inexplicably sad, depressed, disconnected, isolated, withdrawn, empty, feeling cut off from the world around me for no apparent reason. Certainly, China was as fascinating and the people as hospitable as ever, so it wasn’t that. In retrospect, I think I had the symptoms of Seasonal Affective Disorder (about as accurate an acronym as there ever was), though I’d never once before experienced SAD in my life. I acted happy in front of others, but it was just that, an act, and it bothered me that I even had to act. 
Near as I can tell, the only thing missing was I didn’t have a book to read.
My mood improved slightly upon my return to America, but only slightly; and as I drove back to college in Idaho, I couldn’t shake the feeling that the whole world, even in all its natural glory and splendor, was nothing but a prison to me now. It wasn’t just China. It was giving me the heebie-jeebies, truth be told.
Now, Idaho in the dead of winter will hardly improve anyone’s SAD, but the heavy course-load and constant reading of my senior year at least distracted my mind for the time being.
Then I read two books that changed my life.
It so happened that a Spanish professor, out of the blue, recommended me Zen and the Art of Motorcycle Maintenance, a book I hadn’t even heard of till that morning. Less than two hours later, a classmate in a completely different class, again apropos of nothing, made the same recommendation. Taking these two disconnected suggestions as a sign, I checked Zen out. I meant to fit it in during downtime at work, perhaps over the course of a month.
I finished it in less than a week. I’d never encountered a page-turner like it—no, not even among thrillers and mysteries.
Later that Spring, I was assigned Joyce’s A Portrait of the Artist as a Young Man for an English class. My mind still hasn’t recovered from the shock: I didn’t know you could write like that! I didn’t know you could read like that. Somehow the one-two punch of Zen and Portrait shook me from my doldrums, woke me up, opened my eyes to the stunning beauty of the universe, reconnected me to everything and everyone, enlarged my mind and expanded my soul.
Since then, I haven’t chanced it: I read books constantly. Non-stop. One after another. I haven’t had a bout with SAD since. Some folks have assumed my voluminous reading—and inevitable writing—to be an act of pretension, but really, it’s one of desperation: an act of sanity in an insane world. It’s been cheaper than therapy. Literature, quite simply, keeps me sane.