A perplexing but ignored question concerning the pervasion of divination and fortune-telling in Chinese societies is how the diviners are able to convince people that they have actual access to the secret of Heaven. Their success is explained in this essay by examining how the diviners strategically make use of a procedure that appears to be in accordance with the course of Heaven, called "heavenification," (擬天手法) to build apparent connections with Heaven. Heavenification is a complex process of rhetoric. There are, in theory, infinite ways in which Heaven and human beings can be compared. What specific parallels should be drawn for the benefit of the diviners to establish communication with Heaven and, more importantly, to persuade other people to accept this communication is not an easy decision. The diviners have to take into consideration not only their contemporaries' understanding of the concept of Heaven but also their expectation of what the will of Heaven might appear to be at the time. The book of changes, or Zhouyi (《周易》), accepted for thousands of years as the key to the mystery of transformation, is a classic example of this rhetorical construction. This essay analyzes the method of heavenification used in Yizhuan, the Commentaries appended to Zhouyi. The analysis shows that the commentators have systematically interpreted Zhouyi and established a legendary status for it as a book "containing the measure of heaven and earth," thus legitimizing its position in predicting and explaining the will of Heaven in China.