Eternity's Heartbeat, a song for soprano and piano, was composed for inclusion in the performance of Hatzis' percussion concerto Tongues of Fire, commissioned by the Scotia Festival of Music for percussionists Beverley Johnston and Evelyn Glennie.It is intended to be performed between the first and second movement of the concerto and contains the main thematic material of the second movement.

The original version of this song (in a different key) was recorded by soprano Patricia Rozario and pianist Peter Allen and included in the premiere performance of Tongues of Fire, in Halifax Nova Scotia on June 11, 2007.

The composer wrote this stand-alone version to be used as an "encore" piece at the end of a vocal concert. At the request of Evelyn Glennie, Eternity's Heartbeat now exists in a number of different instrumental configurations, for solo marimba, solo piano, marimba and piano and piano four hands.