First, practice determines understanding.
1. Practice is the source of knowledge. Knowledge can only be produced on the basis of practice. As Mao Zedong said, "If you want to know the taste of pears, you must taste them first", and for example, "You won't know your parents' kindness until you raise children", "You won't know how expensive rice is until you are in charge" and "Nothing ventured, nothing gained" all show that practice is the source of knowledge, and it is the only source.
2. Practice is the driving force of cognitive development. The development of practice constantly puts forward new topics of cognition and promotes the development of cognition. As Engels said: "Once there is a technical demand in society, this demand will push science to more than ten universities." In daily life, farmers' farming has promoted the emergence of agronomy, and the demand of construction industry has promoted the development of mathematics, architecture and other disciplines. ② Practice provides necessary conditions for cognitive development. On the one hand, the development of practice constantly reveals more and more characteristics of the objective world and accumulates more and more rich experience materials for solving new cognitive problems; On the other hand, practice provides increasingly complete material means for continuously strengthening the cognitive ability of the subject. For example, the invention of microscope and the appearance of FAST, the largest spherical radio telescope in China, provided better tools and promoted the development of knowledge. ③ Practice and exercise to improve the cognitive ability of the subject. As Engels said, "human wisdom develops according to how people learn to change nature".
3. Practice is the purpose and destination of cognition. The purpose of cognitive activity is not to know the activity itself, but to better transform the object and guide practice more effectively. Just like learning knowledge for application, inventing light bulbs for lighting and so on. Explain that the purpose and destination of cognition lies in guiding practice.
4. Practice is the only criterion to test whether knowledge has truth. As Aristotle once pointed out, the speed of falling objects is directly proportional to their mass. The heavier the objects, the faster they fall. Galileo believed that the speed of a falling object had nothing to do with its mass, and that two iron balls should land at the same time. Two people who know the truth correctly can only be tested by practice.
Second, the guiding role of cognition in practice
The reaction of cognition to practice is twofold: 1. Correct understanding has a positive role in promoting practice; 2. Wrong understanding will negatively hinder practice and even lead to the failure of practice.