“Extending one’s knowledge” in the Great Learning marks the pivotal movement from inner awareness to outer order. It is described as the step that follows the investigation of things and precedes the making of the will sincere, thus functioning as a bridge between careful inquiry and firm moral commitment. This knowledge is not a stockpiling of information, but a clarification of the principles present in things, especially in human relationships and moral situations. By discerning these principles, the mind is illuminated and confusion about right and wrong is dispelled. In this way, extending knowledge becomes the foundation upon which sincerity of intention, rectification of the mind, and genuine self-cultivation can rest.

The text presents this process within a larger chain that runs from the individual to the world at large: investigating things, extending knowledge, making intentions sincere, rectifying the mind, cultivating the person, regulating the family, governing the state, and bringing peace to the world. Extending knowledge is therefore not an isolated exercise in contemplation, but an indispensable early step that undergirds the entire sequence. When understanding is clear, moral judgment becomes reliable, and the will can align itself without hesitation to what is recognized as right. From such cultivated persons, ordered families and well-governed states naturally emerge, giving social harmony a firm ethical basis rather than leaving it to chance or mere custom.

The kind of knowledge at stake is inherently practical and ethical. To “know” in this context is to grasp the moral order that runs through things and to allow that insight to shape conduct; knowledge that does not issue in action is not regarded as genuine. Extending one’s knowledge thus involves a sustained investigation into the nature of things and situations so that the underlying principles of proper conduct can be discerned and embodied. As this moral understanding deepens, the mind becomes steady, the will sincere, and behavior more fully aligned with the Way, allowing personal virtue and social harmony to arise from the same clarified source.