Try to explain the contribution of the four great inventions to the world and the reason why China's modern science and technology gradually lags behind the West.

The invention of ancient papermaking, movable type printing, gunpowder and compass in China once made our traditional science and technology at the leading level in the world for a long time. Their contribution to the world mainly lies in papermaking and printing, which provides favorable conditions for the cultural, educational, political and economic development of all countries in the world and promotes the exchange of world ideas and cultures. Gunpowder and compass have played a great role in the development of world politics, military affairs, commerce and navigation. It changed the whole process of human history and civilization and led to the emergence of the world market.

The main reason why China's modern science and technology gradually lagged behind the West was that the nature and system of China's traditional agricultural society and the lack of pioneering social production restricted and hindered the popularization, application and development of the four great inventions and many scientific and technological achievements, which made China's modern science and technology gradually lag behind the West.