This old tune by Chicago has been in my brain all day long.
Only super-talented musicians could perform this tune with its widely varying time signatures. Written and with a lead vocal by Robert Lamm, composer and singer on several of the band's earliest hits, A Hit by Varese, gives all of the original members of Chicago a chance to show their chops.
A band that included both formally trained and more instinctive musicians, Chicago's early work, including this song, presented a brilliant fusion of jazz and rock.
This is not one of their better known pieces. But it is definitely one of my favorites.