What lies before us and what lies behind us are small matters compared to what lies within us. And when we bring what is within out into the world, miracles happen.
Source, in full
Attributed to Thoreau, in The Life You Were Born to Live: A Guide to Finding Your Life Purpose (1995) by Dan Millman, p. xi, and to Ralph Waldo Emerson in Promotion of Pharmaceuticals: Issues, Trends, Options (1993) by Dev S. Pathak, Alan Escovitz, and Suzan Kucukarslan, p. 74, but no occurrence of it prior to the 1990s has been located.