Three of the cleanest-shaven men in the world are beaming. For 27 years the third blade, like Darwin's missing link or Fermat's last theorem, had eluded them. The idea of three blades dancing on the head of a razor was so preposterous that Saturday Night Live used it as a commercial parody in 1975. To the engineers at Gillette, that joke was a cruel mockery, a searing reminder of their limitations.
Last Tuesday the shame disappeared. Gillette is unveiling the Mach3, the three-bladed wonder these three engineers had often glimpsed but never captured. Giddy for men of their age and earnestness,...