A man is like a bit of Labrador spar, which has no lustre as...

A man is like a bit of Labrador spar, which has no lustre as you turn it in your hand until you come to a particular angle; then it shows deep and beautiful colors. There is no adaptation or universal applicability in men, but each has his special Talent, and the mastery of Successful men consists in adroitly keeping themselves where and when that turn shall be oftenest to be practiced.