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The hardness of a diamond is part of its usefulness, but its true value is in the light that shines through it.

B.K.S. Iyengar, John J. Evans, Douglas Abrams (2006). “Light on Life: The Yoga Journey to Wholeness, Inner Peace, and Ultimate Freedom”, p.27, Rodale
The hardness of a diamond is part of its usefulness, but its true value is in the light that shines through it.