I am going to see one of my heroes tomorrow night for the first, and certainly the last, time. The country singer Glen Campbell is performing at the Royal Festival Hall in London on the second night of the tour he is calling "The Final Farewell".
Be sure, too, that this is not one of those cynical publicity stunts, beloved of musicians of all types. Are you going to so-and-so's farewell tour. No, I think I'll wait for the next one. There will be no next time for the 75-year-old Campbell, who is suffering from Alzheimer's disease and is finding it increasingly hard to function.
The music critic Neil McCormick met Campbell this week, and described it as "the most heartbreaking interview I have ever done". The singer was so confused by his surroundings, and puzzled by his purpose, that his wife, Kim, had to answer many of the questions, and fill in the blanks left by her husband.
Kim and Glen have been married for 29 years, and she is his fourth wife, so it's clear that Campbell packed quite a lot into his younger life. That includes a fairly lively relationship with drink and drugs, although he has been mostly clean for a long time now. In some people's eyes, he had an equally unhealthy weakness for the wilder shores of Republicanism, which includes a friendship with the gun-toting Charlton Heston.
Religion has also played a large part in his life – he peppers his conversation with references to the Lord, and will be appearing on BBC's Songs of Praise on Sunday – and has said that he and Kim are long-time followers of Messianic Judaism.
But, uncertain and stumbling as he is when speaking, Campbell can, by all accounts, still do the business on stage. Music has long been seen as a way of easing the pain of Alzheimer's, and research has shown that the relentless march of the disease can be slowed when patients listen to their favourite music, which acts as a potent trigger for recalling vivid memories.
Certainly, in Campbell's case, without the music, he would be a much more tragic figure. It has enabled him to be philosophical about his disease – "I'm upright and breathing. It's wonderful," he told McCormick – and given him the chance to depart the stage in a dignified and, let's face it, heroic manner.
It's hard to know what we'll all feel tomorrow night, the joy of hearing him sing Jimmy Webb's unforgettable words – "I need you more than want you/And I want you for all time" – mixed with the pain of knowing we'll never see or hear its like again.
Part of our lives is passing before our eyes, and that can't make you feel anything other than sad.