Homeric hymns praised Hephaestus, Greek god of fire and craftsmen, for teaching men to build and burn their way out of the caves. But the celebration of craftsman as civilizers quieted as city walls grew thicker, and the luxury of a mental life has come to seem distinct from the manual labor that made it possible.

The cover of Richard Sennett’s new book “The Craftsman” (Yale University Press, 326 pages, $27.50) frames a typical image of the craftsman today: a bucolic, stout-hearted artisan smeared with sweat and crude oil. “Craftsman” is a fairly concrete, unvarnished word that Mr. Sennett gilds and bejewels with virtue and history. For Mr. Sennett, craftsmanship “represents the special human condition of being engaged,” an ideal marriage of “hand and head” that crowns technical mastery with a person’s sincerest efforts to make something well for its own sake. This would be dizzily heady stuff if Mr. Sennett’s book weren’t so prodigiously grounded in stuff itself as a means of knowledge.

The practice of the craftsman is always richer than the rules that guide his craft; no one learns to catch a football by reading the coach’s playbook. This notion of tacit knowledge — information that one can’t quite abstract or express — informs Mr. Sennett’s principle that making is thinking — an extension of the maxim that doing is learning. The mentor’s burden of teaching an apprentice is largely eased by the workshop itself.

The industrial culture that erupted in the 19th century has made every effort to outmode apprenticeships by formulizing quality. Henry Ford saw that an assembly line of bored workers would build cars better, and more quickly, than a smaller team of skilled mechanics, and Ford’s heirs saw that fully computerized production would only multiply the improvement.

But while a soulless factory befits a soulless craft, Fordist approaches have little success with any task that aims beyond trading hands for microchips. The skills and standards of a community must instruct, but not smother, the individuals who practice them. Where the shabby construction projects of Marxist Russia demeaned workers as faceless shards of a national effort, Japanese manufacturing plants — in which competition and open criticism reflect each individual’s contribution — have flourished for 50 years, even in a country known for its conformity.

Great craftsmanship, Mr. Sennett reminds us, is highly individual and uncannily impressionistic — these are traits that both free the craftsman and imperil his particular legacy. After Stradivari died, his miraculous violin workshop failed within a generation, because his methods were so neatly bound with the subtle touch and vision of his genius. He had a transcendent set of skills to which all his apprentices, including his two sons, would finally remain unequal servants.

Fully understanding a craft, then, lies not only in the plans but in the process itself, where tacit knowledge takes form. Moreover, the journey of error, ambiguity, and reflection constitutes a wholly personal — and therefore truly ethical — engagement with a craft, without which there is no comprehensive grasp of the ends trailing its means.

Aristotle, Mr. Sennett observes, deemed architects superior to artisans because they knew why things were built a certain way, not merely how. Mr. Sennett begs to differ, arguing that the knowledge of craftsmen, and the dignity with which they strive for excellence, is easily as noble as drafting blueprints. Physical work can and should marry know-how to know-why, he writes. This is a curious contention, for Mr. Sennett’s ideal craftsman owes a wholesale — and basically unmentioned — debt to Aristotle’s phronemos: a practically wise person with both the experience to act skillfully and the judgment to act ethically.

Some sociologists, in a mad dash to visit their thesis upon every known era, make a motley patchwork quilt of history; Mr. Sennett’s work is a smooth, many-colored Persian rug of a study, threading together any instance, ancient or modern, with matching examples of how and why people make things well. These values apply equally to metaphorical crafts: In Mr. Sennett’s scope, parenting and religious rites share equal footing with metallurgy and brickmaking.

Yet as Mr. Sennett establishes in his prologue, the stakes of understanding the fecund union of “hand and head” loom larger than better products and happier workers. The Enlightenment dream that an age of invention and inquiry would perfect civilization has been remolded into a modern Pandora’s Box, bearing the dystopian threat that human life will be diminished by machines that think for us, or destroyed by machines that kill for us. If we salvage an ethical engagement as craftsmen, we may be less likely to make first and ask questions later.

Mr. Axelrod is an editor of Contemporary Poetry Review. He has contributed to Parnassus, New Partisan, and other publications.