Summary
Xí (習) means practice or habituation in classical Chinese. It’s the word in a saying attributed to Confucius (Analects 17.2): by nature people are close to one another; by practice they grow far apart. Xunzi, a Confucian philosopher of the 3rd century BCE, built a theory on the idea. People are born with wayward tendencies, he argued, and become good only through conscious effort: a teacher’s guidance and ritual (lǐ 禮), the rites and regulations handed down from the sage kings. With these, anyone in the street can become a sage.
Earlier Confucians disagreed. Mencius held that people are good by nature and that bad surroundings corrupt them.
Rationale
We use this with a caveat. Xunzi’s view that character forms through repeated practice fits our “cultural habits”, but his rites correct people towards a fixed order, nearer “engineering a shift” than cultivation.