High Quality Content by WIKIPEDIA articles! XXV: The Essential is a compilation album written and mostly performed by Mike Oldfield. THe Roman numerals XXV are to represent that this is a compilation pieces of the first 25 years of Oldfield's work. THe 14 track album features songs from the first 25 years of Oldfield's career, when he was on the Virgin Records and Warner Music labels. THe track "Tubular Bells III" is an early version of the main introduction theme ("Source of Secrets") from Oldfield's then forthcoming album, Tubular Bells III. THe differences between this version and the album version are there is a male vocal instead of a female vocal and there is different instrumentation. AN album or record album is a collection of related audio or music tracks distributed to the public.