The "Thor: The Dark World" star imparted a wealth of knowledge on the future alumni and credited the Ivy League school for giving her the wherewithal to continue with her acting rather than pursue a career for "seriousness' sake."
"I'm still insecure about my own worthiness," she said of delivering the address, adding that it was "genuinely one of the most exciting things" she's ever been asked to do.
Indeed, comedian Will Ferrell addressed her Class Day 12 years earlier, during a time when the audience she was speaking to was still in kindergarten -- both facts that she readily noted.
"Today I feel much like I did when I came to Harvard yard as a freshman in 1999. ... I felt like there had some mistake, that I wasn't smart enough to be in this company. And that every time I opened my mouth, I would have to prove that I wasn't just a dumb actress," she said. "So I start with an apology, this won't be very funny. I'm not a comedian and I didn't get a ghostwriter. But I am here to tell you today Harvard is giving you all diplomas tomorrow. You are here for a reason."
The 33-year-old, who arrived in Cambridge just after the release of "Star Wars: Episode I," started off with a cautionary tale about her 4-year-old son Aleph's prize-oriented behavior. She then reflected on her four years, but didn't completely romanticize the experience. Portman actually highlighted several dark moments on campus and stated how she was "completely overwhelmed" when she first arrived because she felt a lack of merit and the fact that she'd never written a 10-page paper.
"I had been acting since I was 11 but I thought acting was too frivolous and certainly not meaningful. I came from an family of academics and was very concerned with taking it seriously," Portman said. "I couldn't shake my self-doubt.... I got in only because I was famous: that was how others saw me, that was how I saw myself."
After seeing that her peers, several of whom told her they would be president someday, were taking classes on "fairy tales and 'The Matrix,'" the actress lightened up and shifted her perspective.
"I realized that seriousness for seriousness' sake was its own kind of trophy and a dubious one," she said. "There was a reason I was an actor. I love what I do. And I saw from my peers and my mentors that that was not only an acceptable reason, it was the best reason.
"After four years of trying to get excited about something else, I admitted to myself that I couldn't wait to go back and make more films. I wanted to tell stories, to imagine the lives of others and help others do the same. I had found or perhaps reclaimed my reason."
Portman said that her Harvard degree represents "the curiosity and invention that were encouraged here" and "the friendships" she's sustained.
She decided when she returned to Hollywood that she would only take on projects she cared about and not have her meaning "be determined by box office receipts or prestige." That mentality is ultimately what led her to take on the "artistic risk" of "Black Swan," the ballet film that earned her an Oscar and led to her marrying choreographer Benjamin Millepied.
"It didn't feel like courage or daring that drew me to it. I was so oblivious to my own limits that I did things that I was woefully unprepared to do. And so the very inexperience that in college had made me feel insecure and made me want to play by others' rules now was making me actually take risks I didn't even realize were risks," she said. "If I had known my own limitations, I never would have taken the risk. And the risk led to one of my greatest artistic and personal experiences, in that I not only felt completely free, I met my husband during filming. "
The actress recently completed "A Tale of Love and Darkness," an all-Hebrew film that she directed and starred in and one that she felt "completely unprepared" to take on. She called it "the deepest and most meaningful" experience of her career.
"Making movies, admittedly, has less drastic consequences than most professions and allows for a lot of effects that make up for mistakes," she said. "The thing I'm saying is make use of the fact that you don't doubt yourself too much right now. As we get older we get more realistic and that includes about our own abilities or lack thereof and that realism does us no favors."
Portman used her "obliviousness" and "inexperience" as assets and encouraged the students to do the same.
"If your reasons are your own, your path -- even if it's a strange and clumsy path -- will be wholly yours and you will control the rewards of what you do if you make your internal path fulfilling," she said.
She concluded by noting that the friends she made at Harvard were still friends she had now.
"Grab the good people around you. Don't let them go," she said. "The biggest asset this school offers you is a group of peers that will be both your family and your school for life."
Follow me on Twitter @NardineSaad.