The quote, "Progress would not have been the rarity it is if the early food had not been the late poison," by Walter Bagehot, is a metaphorical statement that delivers a profound message about change, growth, and adaptation.

The "early food" in this quote can be interpreted as habits, beliefs, or systems that were initially beneficial or necessary for survival or growth. Over time, however, as circumstances change, these same habits or beliefs can become "late poison," meaning they become detrimental, stifling progress instead of fostering it. The idea is that what was once beneficial can become harmful if it is not adapted or changed according to new circumstances or knowledge.

In the context of personal development, this quote can serve as a reminder that growth often requires change. What worked for us in the past may not work for us in the present or future. For instance, a person might have developed a habit of working long hours to advance their career. While this might have been beneficial early in their career, over time, it could lead to burnout and negatively affect their health and personal relationships. Hence, what was once "food" (a source of growth and progress) has become "poison" (a source of harm).

In today’s world, this quote can be applied to various sectors. For example, in the environmental context, early industrialization (the "food") led to significant progress in terms of economic growth and technological advancements. However, the same industrial practices have led to environmental degradation and climate change (the "late poison"), threatening our planet’s health and survival.

The quote, therefore, serves as a reminder that progress is not just about moving forward but also about adapting and evolving. It’s about reassessing our habits, beliefs, and systems regularly to ensure that they are still serving us and not hindering our growth or survival.