One of the most beautiful songs ever written. Here is a 1974 performance by Tim for the Old Grey Whistle Test, accompanied by Charlie Whitney on guitar, Tim Hinkley, bass, and Ian Wallace, drums.
Here is the original, from the 1966 album The Many Sides of Fred Neil. Fred actually spent the latter part of his life looking after dolphins, bless him.
And here is a pretty creditable version by Nick Cave, from 2003.