“A minimum of sound to a maximum of sense” is Mark Twain’s aphoristic definition of the aphorism. James Geary defines it, with half a nod to William Blake, in the title of his delightful new book, “The World in a Phrase” (Bloomsbury, 224 pages, $19.95). Mr. Geary, who is the deputy editor of Time magazine Europe, has been in love with aphorisms since he was around 8 and discovered them in the “Quotable Quotes” section of Reader’s Digest. This very personal history of the aphorism is his declaration of love.

It’s particularly appropriate as, when he was a student, Mr. Geary engaged in a bit of performance art, passing out aphorisms for each member of the audience to read. One young woman, with some confusion, read Auden’s “Knowledge may have its purposes, but guessing is always more fun than knowing.” The next day in his mailbox he found a slip of paper saying, “In some cases, knowing is much more fun than guessing.” He remembered who read the Auden aphorism. She eventually became his wife.

An aphorism is not easy to define. Twain’s and Mr. Geary’s definitions don’t quite make sense unless you already know what an aphorism is. There are five criteria for an aphorism. It should be brief, definitive, and personal. It should have a “twist” (a “verbal pirouette”), and it should be philosophical. “Why aphorisms?” asks Mr. Geary.

Because they’re just the right size to hold the swift insights and fresh observations that are the raw data of the wisdom of the ages. Aphorisms are literature’s hand luggage. Light and compact, they fit easily into the overhead compartment of your brain and contain everything you need to get through a rough day at the office or a dark night of the soul.

The aphorism is one of the oldest of literary genres. In early societies where literacy was reserved for the few, these short, punchy sayings stuck in the mind. Mr. Geary cites the Upanishads, Ecclesiastes, and the Proverbs of Solomon as early collections of aphorisms, as well as the earliest work of all of the wisdom literature, the “I Ching.” Lao-tzu, Buddha, Confucius, Muhammad, and the Zen masters were all early practitioners of the aphorism. So was Jesus. The Sermon on the Mount is a string of memorable aphorisms.

Oddly, Mr. Geary chooses to quote the Jesus of the Gnostic Gospel of Thomas rather than the canonical gospels. This is a Jesus who is “a sage rather than a savior,” but perhaps because Thomas’s Gospel didn’t have the advantage of being translated into Jacobean English, Jesus’s aphorisms seem a bit insipid. An example: “Do not worry, from morning to evening and from evening to morning, about what you will wear.”

Mr. Geary’s catalog of aphorists is a selective Who’s Who of the pithy in literature and philosophy: Heraclitus, Diogenes, Epicurus, Seneca, Epictetus, and Marcus Aurelius; Montaigne in his tower and the cynical La Rouchefoucauld; Spinoza, Schopenhauer, and Nietzsche (Mr. Geary’s “Evil Knievel of philosophy”); Wittgenstein and the dour Romanian E.M. Cioran (“To live is to lose ground”). Strangely missing is Pascal, though he is mentioned in passing. His “The heart has its reasons that reason knows not of” is the mantra of all befuddled lovers.

One of the great joys of the book is the emphasis on an assortment of less known writers like Georg Christoph Lichtenberg (“The most entertaining surface on earth is the human face”), Chamfort (“Celebrity: the advantage of being known by those who do not know you”),Vauvenargues (“Necessity saves us the trouble of choosing”), and the “great apostle of the aphorism,” Joseph Joubert (“If there is a man tormented by the accursed ambition to put a whole book in a page, a whole page in a sentence, and that sentence in one word, I am he”). Mr. Geary piques interest in these not-quite-jolly fellows, and we want to read more. Of course the book would be incomplete without Ben Franklin, Emerson, Thoreau, Mark Twain whom I’ve already quoted, and Ambrose Bierce, celebrant of the “worst of all possible worlds.”

In an unexpected chapter, Mr. Geary pays his respects to the writers of light verse, Dorothy Parker, Dr. Seuss, and Samuel Hoffenstein (author of “Poems in Praise of Practically Nothing”), as well as four who hardly fit into the Procrustean bed of light verse, though they did have a light touch: Alexander Pope, William Blake, Edward Fitzgerald’s Omar Khayyam, and Emily Dickinson.

Finally, he considers some 20th-century aphorists, the scathing Karl Kraus, Antonio Porchia, Malcolm de Chazal, Stanislaw Jerzy Lec (“Life is too short to write long things”), Barbara Kruger, and Jenny Holzer. All but Kraus were unknown to me, and they are not all up to the standard of their predecessors. Barbara Kruger’s “I shop therefore I am” doesn’t quite cut the mustard.

So many of the aphorists Mr. Geary considers have a cynical turn of mind. Yet it is bracing to receive their little electric shocks to our most fondly held prejudices. They do, in fact, make us think. And if they don’t quite offer us a world in a phrase, they yet offer some extraordinary phrases that any lover of the prickly thought and the graceful sentence can savor. “The World in a Phrase” is a delight, and Mr. Geary’s love for his subject wonderfully infectious.

Mr. Volkmer, the deputy treasurer of the village of Southampton, writes regularly about books and music for the Southampton Press.