What is called a substance? Give examples of physical bodies and substances.

The substance is the constituent of physical bodies. For example, a plastic cup is the body, plastic is the substance that makes it up. By analogy: a cast iron pan is a body, cast iron is a substance.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.