Ruzbek takes up less room than his broad, sloping shoulders suggest, turning sideways through doorways and keeping to the edge of a gathering. When he waits, he rests his weight on the balls of his feet, as if listening for a floorboard's opinion before trusting it. His long white hair is tied back with a strip of blue cloth, and his eyebrows bristle like pale brushes. His robe cuffs are patched in mismatched squares, each repair done in a different stitch. He moves with careful economy, but when an idea catches him he leans forward so abruptly that nearby people often lean back. The unexpected detail: he carries a tiny wooden toy horse with one wheel instead of a leg, and absent-mindedly rolls it along his knuckles while discussing philosophy.

Ruzbek is patient with a novice's clumsy first attempt and impatient with a powerful person's claim to unquestionable authority. He delights in disputation, yet dislikes humiliating an opponent; when calm he offers examples and questions, while under pressure he becomes blunt and practical. He accepts flaws in objects more readily than failings in people, and sometimes hides his own tenderness behind a lesson.

Ruzbek grew up in a family of potters in the hill town of Vardesh, where his mother taught that a vessel's cracks could tell you where it had been and what it had survived. As a young scholar, he became an apprentice to Master Ovan, a celebrated maker of astrolabes who insisted that every instrument could be perfected if its maker was clever enough. Ruzbek spent years trying to achieve that impossible standard. The turning point came when a frost split the observatory's roof and ruined the masterwork instrument he had labored over for a decade. Ovan blamed Ruzbek and ordered him to hide the damage. Ruzbek instead displayed the broken instrument, showing how its warped brass caught the winter stars in a pattern the flawless model never had. The scandal ended his apprenticeship, but began his life as a traveling teacher. He now lives above a mending shop in the town of Bellwether, where he advises craftspeople, keeps a small public library, and argues with anyone who mistakes uniformity for beauty. His former mentor still sends him letters demanding an apology. Ruzbek's apprentice, Tavi, wants to leave town and study engineering, while his old friend Sella, a potter, quietly fears that Ruzbek's radical acceptance of flaws will keep him from confronting avoidable harm.