When I use a word . . . Powers of three

Triads, triplets, trilogies, tricolons, and hendiatrises—all terms for groups of three things that make a harmonious advertising or political slogan or tell a story of some sort. Three is seductive: one is alone, two may want a divorce, but three offer the chance of mediation. And the rhythm of the words is important. Examples of different sorts of triads include the many groups of three individuals (triplets) in mythologies and religions, sets of three books (trilogies) such as <i>The Deptford Trilogy</i> by Robertson Davies, F D Roosevelt’s advice to speakers “be sincere, be brief, be seated” (a tricolon), and Matthew’s “For thine is the kingdom, and the power, and the glory” (a hendiatris).