Remember back to the 70s and the birth of the ecological "green" movement. All we heard was doom and gloom - and we needed to, look at how our excesses were (and still are!) ruining this planet. Joni Mitchell was singing about turning paradise into car parks while Albert Hammond told us to avoid the pollution in the rivers. And Cat Stevens wondered where the children would play.
Then there was Bowie, offering some hope for the future and telling us to hang in there, things can get better, we can do it. I needed his optimism, then. And I feel ineffably sad tonight.