The default response to sustained rejection is to conclude that the rejection is justified, to recalibrate one’s assessment of one’s own work in the direction of external feedback.

Mary Kenner did not do this.

She knew her inventions were good, and she kept working.

This self-knowledge — the accurate assessment of one’s own work that persists even when the external world is not confirming it — is itself a form of intelligence.

It is a capacity that is poorly served by the success narratives that tend to dominate the stories we tell about inventors and innovators, because those narratives typically focus on the moment of success and elide the long middle period of sustained effort in the absence of validation.

The long middle period is where most of the actual work of invention happens.