This quote is from Charles Dickens’s “A Christmas Carol” and it uses the simile “dead as a doornail” to emphasize the absolute certainty of Marley’s death. The phrase “The wisdom of our ancestors is in the simile” suggests that there is timeless wisdom to be found within this old saying, as it conveys the idea of finality and irrevocability.

The phrase “dead as a doornail” is an idiomatic expression that dates back to the 14th century. The doornail was the heavy studded nails used in olden days for strengthening doors. Once a doornail was hammered in, it was impossible to reuse it. Hence, it symbolizes a point of no return or a state of irreversible finality.

In the context of personal development or in today’s world, this quote may serve as a reminder of the finality of certain actions, decisions, or events. Once something is done, it often cannot be undone. It’s a reminder to think carefully before taking irreversible actions or making life-altering decisions.

Additionally, it also highlights the value of wisdom that has been passed down through generations. Even though the world has changed dramatically, there’s still much to learn from the past. Our ancestors’ wisdom, encapsulated in such sayings, can offer insights into human nature, life, and the world that remain relevant today.

In a broader sense, it can be seen as a call to respect and preserve cultural heritage and tradition, to remember that progress and modernity should not entail completely disregarding the past. It’s about finding a balance between respecting the wisdom of the past and embracing the possibilities of the future.