Dialectics has been defined as the science of connections and also as the science of the universal laws of all motion and development. The principle of universal connection is considered in close unity with the principle of motion and development, for connection in the material world means interconnection and interaction is motion and development. The whole of nature accessible to people forms a system, an interconnected totality of bodies and by bodies it is understood here all material existences. These bodies are interconnected and react on one another. Thus, it is this mutual reaction that constitutes motion. That is why when dialectics is defined as the science of universal connections, the laws of motion and development. At the same time, in defining dialectics as the science of the universal laws of all motion, it is also implied universal connections, for there are no connections without interaction or motion, just as there is no motion without connections or interaction.
The dialectics materialism starts from the material unity of the world and the objectivity of all forms of motion and development of matter. Its materialist nature is most pronounced in the doctrine of objective and subjective dialectics. As a result, objective dialectics is motion and development in the material world itself as in an integral, interconnected whole. Subjective dialectics or dialectical thinking is the motion and development of thoughts, concepts etc which reflect objective dialectics in the human consciousness. Being a reflection of objective dialectics, subjective dialectics in its content coincides with the former. Both are governed by the same universal laws.
The subject of dialectics as a science is the universal objective principles of existence and the laws of development of the material world. Objective dialectics constitutes the content of subjective dialectics. That is why its basic laws and categories are simultaneously laws and categories both of being and cognition.