He follows his daddy out of the apartment and through the hall, his whole body engaged in the act of running to the elevator. When his daddy presses the down button we hear our baby say a new word: down. He repeats the word while we wait. The elevator doors open and we all say bye-bye. Later while play-talking on the phone, he clearly says dad no go down. I am torn between excitement at his use of a sentence and sadness that he misses his dad.