Jeffrey Wright is well known around his high school in Louisville, Ky., for his antics as a physics teacher. But it is a simple lecture - one without props or fireballs - that leaves the greatest impression on his students each year. The talk is about Mr. Wright's son and the meaning of life, love and family. Each year, Mr. Wright gives a lecture on his experiences as a parent of a child with special needs. His son, Adam, now 12, has a rare disorder called Joubert syndrome, in which the part of the brain related to balance and movement fails to develop properly. Visually impaired and unable to control his movements, Adam breathes rapidly and doesn't speak. Mr. Wright ... recalls the day Adam was born, and the sadness he felt when he learned of his condition. "The whole thing about where the universe came from? I didn't care. I started asking myself, what was the point of it?" All that changed one day when Mr. Wright ... realized that his son could see and play - that the little boy had an inner life. He and his wife, Nancy, began teaching Adam simple sign language. One day, his son signed "I love you." "There is something a lot greater than energy. There's something a lot greater than entropy. What's the greatest thing?" "Love," his students whisper. "That's what makes the 'why' we exist," Mr. Wright tells the spellbound students.