A comma in costume.
> The em-dash is the most overused piece of typography in the prose of the last three years. This is not the fault of the em-dash. The em-dash, when load-bearing, is the only mark that does what it does. The problem is the cosmetic use.
A cosmetic em-dash arrives when the writer wants a pause but has not earned a comma. The writer types a longer line and the eye fills in the gravitas. The gravitas is borrowed.
> The test: replace the em-dash with a period. Read the two sentences. If they each hold, the em-dash was a hinge — and a period is more honest. If one sentence collapses, the em-dash was load-bearing — keep it.
The doctrine permits one em-dash per long page. Two if both are earned. Four is vanity. Eight is — by the count — a confession.
"An em-dash is a hinge. Hinges bear weight. Breaths do not."