It was 1989.

I was a freshman at Roosevelt High School, full of idealism and hope, all tempered by the usual fears and insecurities of any teenager.

I had just entered a public high school after spending nine years at a small Catholic school with a graduating class of less than 25 students. (And I was valedictorian. Go figure.)

I had big plans — to write the Great American Novel, to get a Ph.D., to save the world. I carried around an anthology of great poetry, from Walt Whitman to Stephen Crane to e.e. cummings, inspired by the way they viewed the world.

And then came “Dead Poets Society.”

This film, directed by Peter Weir, starred a Robin Williams I had never seen before. Prior to that, Williams was that lovable martian who came to Earth from the planet Ork in an egg-shaped spaceship. I couldn’t imagine him as an English teacher who inspires the students of a conservative and aristocratic prep school in Vermont.

And yet, there was he, this comic genius in a role that literally changed my life.

Here’s one of my favorite scenes from the movie.

The poem, “To the Virgins, To Make Much of Time,” inspired me — and many — to live for the day. (In fact, the poem’s first line, “Gather ye rosebuds while ye may,” was my senior dedication in our school’s yearbook.) “Carpe Diem” has become such a cliche because of that movie, but the sentiment will never get old. It should never get old. It’s one of the most important lessons you can learn in life, period.

So imagine my utter shock when this man who made me laugh hysterically, who was as kind as he was funny, who taught me this one important life lesson, died yesterday in his Northern California home in an apparent suicide. He was just 63.

And the most shocking? He suffered from severe depression.

How is that possible?

This man, who made the universe laugh. How could he be depressed?

Depression is a strange thing. It can strangle even the strongest person. And people who cope with depression often find ways to mask it, to hide those dark feelings from the world.

It seems Williams was a master at that.

I wish he could see how much he was loved and cherished. I wonder if that would have changed his mind at the moment he decided to take his life.

It was really too soon.

I remember walking out of the theater moved and shaken. I suddenly felt vulnerable yet alive, the world spread out before me. I could do anything and be anything — and it was terrifying.

It was a movie I thought about often throughout my life. What was my purpose? Where was I going? What would happen to me? And, most importantly, what was worth standing up for — on the top of my desk in a grand gesture of defiance and loyalty with the words, “O captain, my captain”? What was I willing to risk?

I will never forget when Williams’ character, John Keating, explains the meaning of Walt Whitman’s “Oh Me! O Life!”

“O me! O life!… of the questions of these recurring; of the endless trains of the faithless… of cities filled with the foolish; what good amid these, O me, O life?” Answer. That you are here — that life exists, and identity; that the powerful play goes on and you may contribute a verse. That the powerful play goes on and you may contribute a verse. What will your verse be?

Williams knew what his verse was. And he lived it well.