Our textbook $[$Chapter $4],$ in the section about attitudes and assumptions, mentions that

Theory $x$ assumes that the average human being has an inherent dislike of work and will avoid it if possible.

Theory $x$ assumes that the expenditure of physical and mental effort in work is as natural as play or rest.

Theory $x$ assumes that the average human being does not inherently dislike work.

Theory $Y$ assumes that the average human being prefers to be directed, wishes to avoid responsibility, has relatively little ambition, and wants security above all.