“Man is the most astonishing of creatures,” a medieval Sufi mystic wrote, “and yet, he isn’t astonished at himself.” Maybe it’s just as well that we’re not astonished at ourselves. We might have trouble getting through the day. Certain human faculties seem more baffling the more we think about them. The mystery of consciousness is one such. How do thoughts, memories, musings, and fantasies take shape out of the cells and synapses of the brain and nervous system, the fleetingly immaterial out of the grossly material? Sometimes, too, the features we take most for granted are, on closer examination, the most amazing; of these, language is probably the faculty closest to the miraculous that we possess. But here the opposite transformation occurs: For the solid things of the world, we substitute meaningful puffs of breath or written squiggles which others can understand. This truly is amazing. But here an odd paradox crops up. We put our thoughts and feelings into words, but we do so in most situations as naturally as we breathe. How can language be simultaneously conscious and involuntary?

In his new book, David Crystal undertakes to account for virtually every phenomenon connected with this uniquely human ability. In “How Language Works: How Babies Babble, Words Change Meaning, and Languages Live or Die” (Overlook Press, 512 pages, $30), he leaves no phoneme unturned to provide a comprehensive, witty, and lucid explanation of our fabulous loquacity. Mr. Crystal is probably the most articulate and learned historian of language alive. Among his many books, his “The Stories of English” (2004) as well as “The Cambridge Encyclopedia of Language,” which he edited, are now classics.

“How Language Works” is a big but surprisingly succinct book. In 73 compact chapters, Mr. Crystal ranges over everything from the anatomy of the vocal tract to such exotic subjects as the “whistle languages” of the Pyrenees or — my own favorites — the “click” languages of the !Xu tribe of southern Africa (the exclamation point represents one of their 48 “distinct clicks”). He had the genial idea of arranging the book so that it is both an encyclopedia of language and a continuous narrative. You can consult it for quick reference on factual matters — the symbols of the International Phonetic Alphabet or the nature of dyslexia — or you can immerse yourself in such puzzles as “How we choose what to say” and, rather more alarmingly, “How we can’t choose what to say.”

Mr. Crystal loves technical terminology but each of his terms is lucidly explained, without resort to opaque jargon. His descriptions are unfailingly precise and sometimes quite funny. I didn’t know that Donald Duck had a “buccal voice” — produced from air conserved within “the cheek-space” instead of pumped from the lungs — nor did I know what an “eyebrow flash” was, though I’ve given and received many. The “flash”is “used unconsciously when people approach each other and wish to show that they are ready to make social contact. Each person performs a single upward movement of the eyebrows, keeping them raised for about a sixth of a second.”

As Mr. Crystal notes, most linguists have favored spoken over written language in their investigations, partly because so many of the more than 6,000 languages still in use remain unwritten; he considers this a distortion, and rightly so. His treatment of writing systems, as well as of the mechanics of reading, provides a splendid corrective. Even more interesting, however, is his discussion of electronic communication, which he sees as “neither exactly like speech nor exactly like writing.” An e-mail exchange isn’t really comparable to a conversation; all the cues of facial and vocal expression are missing, and there is a time lag between sallies. But it isn’t really traditional writing either. A text on a page remains stable, an electronic communiqué undergoes alteration by either the sender or the receiver, or both; it can be answered interlineally back and forth, “replies within replies within replies — and all unified within the same screen typography.”

Mr. Crystal’s chapters on grammar are especially illuminating. He doesn’t engage in rigid paradigms but shows how grammar makes sentences work. And there’s an almost mathematical elegance in his “tree diagrams” of complex sentences. (What happened to diagramming sentences anyway? This pedagogic method, invented in 19th- century America, and more like a game than a chore, helped kids learn to tell a good sentence from a bad.) In showing how to dismantle a sentence meaningfully, Mr. Crystal reinforces one of his earlier physiological points about how the ear and the brain manage to pluck distinct syllables and words and phrases out of conversational cascades. Grammar may be historical but it isn’t arbitrary; it apparently corresponds to something profound in our makeup.

I have only one small complaint, and an even smaller quibble. Mr. Crystal includes 19 useful figures, extending from anatomical charts of the vocal organs, the ear, the eye, and the brain, to tables of hieroglyphs and pictograms, but these aren’t always well keyed. I searched in vain for the glottis or the “vocal folds” or even the indispensable pharynx on the appropriate chart. The brain diagram omits either Broca’s or Wernicke’s “areas,” though Mr. Crystal draws attention to their importance for speech in cases of brain damage. As for the quibble, he claims that when the consonants “n” and “d” come together in a word, they are sounded as “m.” He gives “hand-bag” as a standard example. I defer to Mr. Crystal’s impeccable ear for English but I’ve never heard anyone call a purse a “ham-bag,” even at the deli.

The saddest chapters of the book describe the ongoing extinction of hundreds of languages. Mr. Crystal puts it quite starkly: “Of the six thousand or so languages in the world about half are going to die out in the course of the present century: 3,000 languages in 1,200 months. That means, on average, there is a language dying out somewhere in the world every two weeks or so.” There are a few success stories amid this catastrophic decline. Both modern Hebrew and Welsh are thriving. (I know that in Quebec an effort is underway to resuscitate Mohawk and Huron; there are similar admirable attempts in England to revive Manx and Cornish.) Languages are nourished by living communities; once these have vanished, the languages which gave them their irreplaceable identity die too. Mr. Crystal supplies a tragic epitaph for these extinctions: “Spoken language leaves no archaeology.”

eormsby@nysun.com