The dentil was a row of small blocks beneath the cornice. Evenly spaced rectangles that lined the edge of the roof like teeth. That is what dentil means. Teeth. The building had teeth and the teeth were decorative and the decoration was a pattern and the pattern was one of the oldest patterns in architecture. The Greeks carved dentils into the Parthenon. Twenty-five hundred years later the brownstones on the Lower East Side have the same teeth. The pattern outlived every empire that used it.

The dentil did nothing structural. The dentil held no weight. The dentil kept no water out. The dentil existed because the human eye needs rhythm. A flat cornice is a sentence without punctuation. The dentils are the commas. The eye moves along the roofline and the dentils break the line into intervals and the intervals create a beat and the beat tells the eye where to rest. Music does the same thing. A rest is not silence. A rest is the space that gives the note before it meaning. The dentil is the rest between the notes of the cornice.

The mason carved the dentil from the same stone as the cornice or the mason cast the dentil in plaster and glued it to the facade. The carved dentil was expensive. The plaster dentil was cheap. From the street you could not tell the difference. From a scaffold you could. The carved dentil had weight and shadow that the plaster dentil imitated but did not own. The plaster dentil was a performance of wealth. The carved dentil was wealth. The street could not tell. The scaffold always could.

The spacing mattered. The gap between dentils was supposed to equal two-thirds the width of the dentil itself. Not wider. Not narrower. Two-thirds. The Greeks figured out the ratio and the ratio was the difference between a cornice that looked right and a cornice that looked wrong and nobody could explain why it looked wrong except that the ratio was off. The eye knows math it cannot describe. The eye sees two-thirds and calls it beautiful. The eye sees three-quarters and calls it uncomfortable. The eye is a mathematician that never went to school.

Nobody carves dentils anymore. They snap vinyl ones onto the soffit and the vinyl dentils are all the same size because the mold is the same and the mold does not know about two-thirds. The vinyl dentil row goes up in an hour. The carved dentil row took a week. The hour produced a product. The week produced a building. A product is something you buy. A building is something you inherit. The vinyl dentils will not be inherited because the vinyl will crack in twenty years and the crack will not be repaired because the vinyl dentil costs less to replace than to fix. Replacement is not repair. Replacement is forgetting.

See also: Cornice, Frieze