You use monkeys, cows and horses, machines, robots, and tools to work. They are not exploited. Their labor does not create value. You are not a capitalist, but a self-employed person. The definition of value is the undifferentiated human labor condensed in commodities. Must understand the concept thoroughly. Note that there is the word human in it. If it is not human labor, it will not create value, let alone create surplus value. Why must human labor be emphasized? This involves the concept of equality. People should be equal. Humans and animals are not equal, and humans and tools are also not equal. People can possess the fruits of animal labor and the fruits of tool labor. This is not called exploitation, it is all right. But people must be equal, and one person cannot possess the fruits of another person’s labor, only that the fruits of each person’s labor belong to each person. If you want to obtain the fruits of other people’s labor, you can only exchange the fruits of your labor with others for the same amount or equivalent value. If a person possesses the fruits of other people’s labor for his own enjoyment without compensation, this is exploitation and cannot be allowed. But two kinds of goods are exchanged. For example, if I exchange rice for tailor’s clothes, how can I know that the exchange is equal? Do you use a scale to measure the weight, or a graduated cylinder to measure the volume? Neither approach is appropriate. It is difficult to judge whether different commodities are equal in quantity. Finally, economists thought of measuring by value. The essence of value is hard work, sweat. Labor requires hard work and sweat. If two kinds of commodities consume the same amount of human hard work, then the two kinds of commodities can be exchanged. No one suffers, no one takes advantage, and no one takes part of the fruits of other people’s labor for free. This is equivalent (value) exchange. Therefore, value is defined as human labor, and only humans can create value. Natural products are not human labor, so they have no value. For example, natural diamonds are natural products and have no value. But mining diamonds consumes human labor, and this part of the value has to be added to the diamonds. The virgin forest and wild fish are of no value. The workers work for the capitalists, and as much value is created by the workers, the capitalists should return the value to the workers. This is also an exchange of value. But in fact, part of the fruits of the workers’ labor is occupied by capitalists. How much capitalists have exploited is measured by surplus value. The worker creates value, and the capitalist returns part of the value to the worker as wages, and the surplus value belongs to him. This is called surplus value. Supplement: You can possess the fruits of labor of animals and machines, and you can exploit them. There is no need to calculate the surplus value, and there is no need to calculate the value of their labor. The labor of machines and nature does not pay hard, and the labor of animals requires hard work, but they are allowed to be exploited, so they do not count the value. Human labor requires hard work, and at the same time it is not allowed to exploit people, so human labor must be valued. To possess a worker’s surplus value free of charge is to possess part of the worker’s hard work free of charge, that is, to possess part of the worker’s fruits of labor free of charge.