Robin Williams in Peter Weir’s “Dead Poets Society.” Courtesy of Touchstone Pictures.

“Come away, O human child!

To the waters and the wild:

With a faery, hand in hand.

For the world’s more full of weeping

than you can understand.”

This infamous poem by William Butler Yeats was recited by Robin Williams in Steven Spielberg’s 2001 film, “A.I.: Artificial Intelligence.” He played Dr. Know, an info-spewing robotic mirage that delivered the typical motormouth riffs that were Williams’ signature trademark, until a request from Haley Joel Osment’s remarkably humanlike “mecha” triggers this startlingly melancholy response. Suddenly the comedic façade evaporates and we hear Williams’ voice convey arresting vulnerability devoid of schtick. These words were given new, heartbreakingly poignant meaning today when it was announced that Williams died of a suspected suicide after battling severe depression.

It’s an impossible task to list the number of ways Robin Williams changed my life. I continue to feel his influence every single day. I see him in my father when I watch him morph from his identity as a veteran social worker and into the gloriously kooky character of Count Nickel, the unofficial school mascot of Thomas Jefferson School in Hoffman Estates, who recites the morning announcements with the same improvisational exuberance as Mrs. Doubtfire. I think of him every time a movie makes me hyperventilate with laughter, which so memorably occurred when I watched his side-splitting impersonations as the shape-shifting genie in “Aladdin.” I see him in every performer who takes the risk in being unashamedly themselves, even if it means going against the grain and refusing to fit into the sort of marketable persona preferred in Hollywood. There was never anyone like Robin Williams and there never will be again.

His great roles are numerous: the spinach-gulping sailor man in “Popeye,” the riotous DJ in “Good Morning Vietnam,” the wisecracking moon in “The Adventuress of Baron Munchausen,” the homeless eccentric in “The Fisher King,” the grown-up Peter Pan in “Hook,” the perpetually out-of-focus actor in “Deconstructing Harry,” the compassionate psychologist in “Good Will Hunting” (a role that deservedly won him an Oscar), the dead man who strives to save the soul of his wife in “What Dreams May Come,” the deranged loner in “One Hour Photo” and, in his last big screen triumph, the long-suffering father in “World’s Greatest Dad,” whose son accidentally succumbs to asphyxiation.

Yet the role that will always tower above them all in my life is the inspirational English teacher, John Keating, in Peter Weir’s Oscar-winning yet much-maligned 1989 drama, “Dead Poets Society.” It was the role that cemented the template for a long series of subsequent Williams roles that often verged into self-parody. It was painful to watch the gifted actor play endless nonconformist clowns in saccharine vehicles like “Patch Adams.” The word saccharine could also be used to describe Weir’s film, where students at an oppressively strict prep school learn to explore life’s boundless possibilities under the tutelage of Keating, who quotes the immortal words of iconic poets while urging the kids to “seize the day” and “make their lives extraordinary.” Though the film has its moments of levity, people tend to forget just how somber a picture this is, and how well-acted by its excellent ensemble of actors led by Robert Sean Leonard, as a free spirit whose intolerant parents drive him to suicide, and Ethan Hawke as the shy boy who is drawn out of his shell by Keating and finds empowerment.

It is Hawke who stands on his desk in defiance of the monstrous headmaster who forces Keating to leave, blaming his radical teaching methods for Leonard’s death. Keating stands in the doorway, his eyes glistening, as he takes one last look at his students, who are all risking expulsion by standing in support of everything he represents. “Thank you, boys,” he says before exiting, “Thank you.” It’s as aggressive a tearjerking moment as anything put on film, but it never fails to move me deeply. Part of the reason is because the scene is directed and acted to perfection. The other reason is because I lived it.

Like practically everyone who ever survived junior high school, my memories of that three-year period were pure hell. I quickly learned that I had two choices: either endure the mortifying ridicule of my dominating peers or become a bully myself (my choice was the former, naturally). I lived each day as quietly as possible, never allowing my voice to be heard for fear of it being attacked. My drama teacher, Mr. Coy, changed all that. He was the life force that awakened my love of theatre and the arts (which eventually led me to find my own community of kindred souls in high school). His ability to bring out the best in his most frightened, antisocial students left me in awe. He was hysterically funny, tirelessly encouraging and a constant joy to behold. His hero, of course, was Robin Williams, and had clearly modeled his classroom demeanor after the man (I remember the “Fisher King” poster that graced his wall).

Not everyone liked Mr. Coy, especially our principal, a loathsome grouch who never once put forth any effort or exuded any interest in engaging with the kids who went to his school. I have no clue how he got the job in the first place, and always picture him finding ecstasy working at Halliburton in an office all by himself. It was widely believed that the cruelty he had shown toward Coy is what caused the beloved teacher to leave the school prior to my eighth grade year. I was beyond devastated. My Captain had vanished without me getting the chance to say goodbye or, at the very least, stand on my desk. And yet, his spirit remained with me and it fueled my determination to get through the last awful year unscathed. Mr. Coy made me believe that it was okay to be who I was, and his message was inspired directly by the character that Williams had created on film. That message, quite simply, saved my life. Thank you, Robin. Thank you.