Meaning: The quote "Be conservative in what you do, be liberal in what you accept from others" is attributed to Jon Postel, a prominent computer scientist and an instrumental figure in the development of the early internet. This quote encapsulates a fundamental principle of designing and implementing systems, particularly in the context of network protocols and standards.

To understand the meaning of the quote, it's important to consider its application in the realm of computer science and specifically in the development of internet protocols. When Postel expressed the idea of being conservative in what you do, he was referring to the concept of being cautious and disciplined in the design and implementation of systems or protocols. This means that when creating new systems or protocols, it is important to be careful, thoughtful, and deliberate in the choices made, ensuring that these decisions are well-considered and maintain a high level of consistency and stability.

This conservative approach can be seen as a means of promoting reliability and predictability in systems. By being conservative in what one does, it helps to avoid unnecessary complexity and unforeseen consequences, leading to more robust and maintainable systems in the long run. In the context of internet protocols, for example, being conservative in what one does could involve adhering to well-established standards and best practices, avoiding unnecessary deviations or innovations that could introduce instability or incompatibility with existing systems.

On the other hand, the latter part of the quote, "be liberal in what you accept from others," suggests a different approach when it comes to interacting with external inputs, such as data or requests from other systems. In this context, being liberal means being open-minded and flexible in accepting and processing a wide range of inputs or behaviors from external sources. This principle is particularly relevant in the context of network communication and interoperability, where systems need to be able to accommodate a diverse set of inputs and adapt to varying conditions.

In the realm of internet protocols and networking, being liberal in what you accept from others is about being able to gracefully handle unexpected or non-conforming inputs, without necessarily rejecting them outright. This flexibility can lead to better interoperability and resilience in the face of diverse and evolving network environments. It also aligns with the principle of graceful degradation, where systems are designed to function reasonably even in the presence of errors or unexpected conditions.

The quote by Jon Postel encapsulates a balanced approach to system design and interaction. It emphasizes the importance of maintaining a level of conservatism and discipline in one's own actions, while also promoting openness and flexibility when dealing with inputs from external sources. This balance is crucial in the development of reliable and interoperable systems, especially in the context of internet protocols and networking, where diverse systems need to communicate and cooperate effectively.

In summary, the quote "Be conservative in what you do, be liberal in what you accept from others" serves as a guiding principle for designers and developers, encouraging them to exercise prudence and discipline in their own actions, while remaining open-minded and adaptable when interacting with external inputs. This principle has had a significant impact on the development of internet protocols and standards, contributing to the robustness and interoperability of the modern internet.