elderly man in his eighties, to his doctor

The elderly man in his eighties, hurried to his doctor appointment at 8am. He wanted to finish quickly because he must be somewhere by nine. The doctor asked what the next appointment was. He proudly said that at 9am every morning he is at the hospital to eat breakfast with his wife. The doctor asked in what condition his wife was in. The man said that his wife had Alzheimers disease, and for the past 5 years she hasn't known who he is. The doctor was surprised and asked the man why he continues to go faithfully if she has no idea who he is....the old man replied, " because I still know who she is. "