thomas quasthoff says he will be devoting more time to teaching with his family.is musical career has long been an inspiration. he overcame serious birth defects to share his gift with music lovers everywhere. ♪ >> thomas quasthoff is often hailed as one of the greatest singers of our time. shot in the musical that his career has come to a sudden end. he says his failing health means he can no longer meet his own high standards. in his almost 40 years as a classical singer, thomas quasthoff has earned four grammy awards. he performed giant world famous concert halls, from vienna to new york, and worked with world- class conductor is. >> it is a great musician an extraordinary man, and everything he sings it is full of the very deepest meaning. >> thomas quasthoff succeeded against great odds. he was born in 1959 with serious birth defects. a music conservatory rejected him because of his handicaps. but he was not deterred. today, he is a conservatory professor. after his retirement, the school be his focus, training young talent to one day take the stage. >> we lo