Definition of spark of life:
(v) :
to emit sparks; to throw off ignited or incandescent particles; to shine as if throwing off sparks; to emit flashes of light; to scintillate; to twinkle; as, the blazing wood sparkles; the stars sparkle; to manifest itself by, or as if by, emitting sparks; to glisten; to flash
"I see bright honor sparkle through your eyes. --- Milton."