"In the beginning, human nature is inherently evil" is Xunzi's view during the Warring States Period, which comes from "Xunzi·Evil Nature".

The original sentence in "Xunzi·Evil Nature":

Today's people are able to transform themselves into masters, accumulate literature, and practice morality, etiquette, and righteousness. Those who violate etiquette and justice are villains. Judging from this, it is obvious that human nature is evil, and its good nature is false.

Vernacular translation: Nowadays, people who can be influenced by teachers and laws, accumulate knowledge of classics, and observe etiquette and justice are called gentlemen; those who indulge in willfulness, are accustomed to wanton debauchery and violate etiquette and justice, are gentlemen. Just a villain. From this point of view, it is obvious that human nature is evil, and their good behaviors are man-made.

Extended information:

The theory of evil nature is naturally less popular than the theory of good nature. In fact, just as the theory of good nature does not allow people to automatically do good, the theory of evil nature does not mean that people are allowed to do evil at will. In its original meaning, the evil of human nature refers to the survival instinct that human beings, as a kind of creature, originally possess. If a living thing wants to survive, it must seek life.

Since we must seek life, there is no need to deny it or avoid it. Xunzi's approach just didn't avoid it. From this point of view, Xunzi points directly to human nature, which is more "based on human feelings" than Mencius' multi-party debate. Mencius' theory started with the theory of the goodness of nature, but ended with the denigration of Yang Mo. Xunzi is notorious for his evil nature, but he has more rationality.

Xun Kuang was a thinker of the emerging landlord class. He was knowledgeable. On the basis of inheriting early Confucianism, he also absorbed the strengths of each school, synthesized and transformed them, established his own ideological system, and developed the ancient materialist tradition. Most of the existing thirty-two chapters of "Xunzi" are Xunzi's own works, involving many aspects of philosophy, logic, politics, and morality.

In terms of his view of nature, he opposed the belief in destiny, ghosts and gods, affirmed that the laws of nature are not subject to human will, and proposed that people should comply with the laws of nature in order to prosper and develop; on the issue of human nature, he proposed "nature" "Evil Theory", which advocates that human nature has two parts: "nature" and "pseudo". Xing (nature) is the evil animal instinct, and pseudo (artificial nature) is the good ritual and music education, denying the innate moral concept.

Baidu Encyclopedia - Theory of Sexual Evil