A co-worker gave me a copy of Haruki Murakami's Kafka on the Shore.

When I first picked up the book, I had planned to read for a few hours; instead, I stopped on the first page. Murakami caught me off guard with his use of opposing word pairs:

Light and dark. Hope and despair. Laughter and sadness. Trust and loneliness.

Kafka was originally published in Japanese, so maybe something was lost in translation. But, the more I thought about trust and loneliness as opposites, the more I believed that Murakami struck at the heart of what loneliness is. It's not about physical solitude. Loneliness is the mental solitude that we suffer when our trust is betrayed.

My acceptance of this definition made me wonder how loneliness relates to depression and what depression really is. This is a brief exploration of those concepts.

When erosion destroys bridges, an island remains

I've had my trust violated more times than I can remember. These indiscretions are usually small, but the big ones stick with you.

In grade school, my best friend stole my prized baseball cards. In middle school, a friend "accidentally" loaded a virus onto my family's computer. (It was obvious that he had created the malware himself and was hoping to live-test the code he had written.) In high school, a dozen students scapegoated me after being caught with alcohol on a school trip. In college, my friends didn't intervene when a pack of hooligans smashed my face with bottles, knocking out my teeth. In the office, a room full of co-workers were oblivious to my hand signals as I choked (I successfully performed the Heimlich maneuver on myself just before blacking out).

Each of these events eroded the trust that I had placed in my friends, acquaintances and peers. I was stuck replaying things in my own mind, thinking in circles and fearing that I was a fool for being trusting in the first place. I felt lonely and my world seemed a little emptier.

The feeling of emptiness creates a vacuum

I'm pretty sure that the first time I felt depressed was during high school. Whenever I felt a "low," I assumed that it was the natural result of having a high. But, as decades passed, depression began to feel more like a sense of gravity: an invisible force that one rarely thinks about, but is always there and always pulling downward. But, not every invisible force is predictable.

I saw the first plane hit on Sept. 11, 2001 and watched in horror as the towers came down. Yet, these nightmarish events filled me with a sense of purpose. Two friends and I volunteered to work in a bucket line at Ground Zero.

The depression came later when I realized that we weren't saving anyone. We were just moving rock because it had to be moved.

What is depression?

I believe that depression is an awareness (not always a knowledge) that one's abilities, skills and remedies are losing relevance or lessening. For example, an athlete might become depressed as his physical talents fade with age. A worker might become depressed when her manual labor is made obsolete by robotics. A soldier might become depressed when his wartime purpose is no longer relevant in peacetime. Anyone may become depressed when he or she recognizes something is wrong, but doesn't know how to solve (or even identify) the problem.

The more we lose trust in others (or even worse, when we lose trust in ourselves), the lonelier we become. And the more time we spend in this emptiness, the more the world moves on without us.

Depression is the relative sensation of feeling lower as others grow higher. Progress is upward, not forward. That's why I believe that enlightenment is the opposite of depression.

Addiction is an easy way in

Taking a drug or compulsively seeking external validation (on social media, for example) isn't enlightening. It's a cheap and temporary high. When an addict comes back down, he or she feels even lower than before. The point of no return is when someone feels so far behind, that there isn't a point in trying anymore. Like Hemingway wrote, these things happen gradually, then suddenly.

Humans don't cope well with sudden change.

Russian suicide rates skyrocketed after the fall of the Soviet Union in 1991. Japanese suicide rates jumped after the banking sector collapsed in 1997. U.S. suicide rates have risen steadily since the Dot Com crash, followed by Sept. 11th, followed by the War on Terror and the Great Recession.

Nevermind the technological disruptions that are happening every day. The rise of loneliness, depression, addiction and suicide may become the new normal.

I'm not suggesting that the world stop progressing. No, my point is that it's more important than ever to be honest, supportive and trustworthy -- real lives are in the balance.