18-year-old Eric Duquette, who didn't speak until the age of five, but now is fluent in Spanish, inspired his high school classmates last week when he delivered a stirring commencement speech.

"My parents were told I would most likely end up in an institution," said Duquette. "I stand before you accepted into every institution of higher learning I applied to." He added with a grin, "So, I guess, in a way, the experts were right about the institution thing."

His is a lesson in perseverance. With devoted parents teaching him a handful of words each day for eight hours, he steadily improved until by his senior year in high school he was studying calculus and honors physics, topping all but one of his 199 classmates with his grade point average.

The Smithfield, Rhode Island student will attend Rhode Island College in the fall, with plans to study biology and eventually become a pharmacist.

(WATCH the inspiring video below, or read the story at ABC News)