You can't interrupt the process of making a key once you've started. It lets a kind of hesitation into the iron. That happens and the key will never sit well in its lock.
In Henning Mankell's book "Before the Frost," the author emphasizes the importance of commitment and focus in any process. He uses the metaphor of making a key to illustrate that once you begin a task, hesitation can lead to mistakes. If one interrupts the process, it can result in flaws that will ultimately prevent the key from fitting properly into its lock, symbolizing how wavering in efforts can compromise the outcome.
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