While guiding the revolution for tens of years, he has enriched President Kim Il Sung's idea, Juche idea, as the guiding idea for the era of independence and given perfect answers to all the theoretical and practical questions arising in the socialist construction through his energetic ideological and theoretical activities.

He, with a firm determination to further develop the revolutionary idea of the President from long ago, has poured his thinking and energy into the deep study of the Juche idea and, at the same time, energetically read and analyzed the preceding theories.

In this course, he became deeply aware that the revolutionary idea of the President is the only guiding idea of the new era.

In the 1970s when the socialist construction was pushed ahead in full swing in the country he formulated the President's idea into an integrated system of idea, theory and methodology of Juche and proclaimed the program of modeling the whole society on the Juche idea.

Although he was busy with the leadership over the overall work of the Party, army and state, he continued energetic ideological and theoretical activities to enrich and develop the Juche idea as the guiding idea for the era of independence.

On March 31, Juche 71 (1982) he made public his famous work "On the Juche Idea" in which he systemized the revolutionary idea in a comprehensive way.

The work elucidates in a scientific and theoretical way the man-centered philosophical outlook on the world, the socio-historical outlook evolved with the popular masses, the maker of history, as the center and the guiding principles of the Juche idea. As soon as the work was published, it evoked a great response at home and abroad.

Kim Jong Il authored more works such as "On Some Problems of Education in the Juche Idea" and "On Having a Correct Viewpoint and Understanding of the Juche Philosophy" and thus further enriched and developed the Juche idea.

In addition, he developed in depth the Juche-oriented theory on socialism based on the guiding idea of the era of independence with his indefatigable ideological and theoretical activities for protecting and glorifying the man-centered Korean-style socialism.

He in his many famous works advanced in an all-round way the tasks to defend and develop the Korean-style socialism based on the scientific guiding idea. Typical of the works are "On Some Problems of the Ideological Foundation of Socialism," "Socialism of Our Country Is a Socialism of Our Style As the Embodiment of the Juche Idea" and "The Historical Lesson in Building Socialism and the General Line of Our Party".

The ideological and theoretical feats he has performed for the country and people, the times and revolution, with his extraordinary wisdom and energetic ideological and theoretical activities will be imperishable forever.