Cesar: yes, I did get these references from Douglas Wiles' book, and I did attribute the reference in my first reply, though it was buried in the text, so perhaps didn't stand out. I'm afraid I really have no idea why the Masters differ so much on the relationship of the Thirteen Postures to the trigams and elements. The only point that they seem to share in common is that they ARE related - somehow, but of course we're no really told why. However, Da Liu, a Taiwanese Yang style practioner who moved to the states published a book called 'T'ai Chi Ch'uan and I Ching', which contains numerous reflections on the relationship. He taught a shortened version of the form similar to Cheng Man Ching's but with more movements, though he advised 'serious students' subsequently to learn the long form. After his form instructions in the book, some 50 pages are taken up with relating all the movements to the Hexagrams (yes, Hexagrams in this case, not trigrams), although he ascribes the component movements of Grasp Bird's Tail and Push Up to trigrams. The movement as a whole he links to Ch'ien, the Creative. For instance, to give an example of his way of thinking, he says: 'The Book of Changes says: "Nine in the second place means: Dragon appearing in the field." The number 9 indicates the unbroken line that is second from the bottom in the hexagram. the phrase "the second place" also refers to the abdomen. The line, "Dragon appearing in the field", is a concrete expression of the first statement, with the dragon represented by the hand and the field understood to be the abdomen. As the hand, or dragon, flies upward to a place in front of the player's chin, the Book of Changes says: "Nine in the fifth place means: Flying Dragon in the Heavens". If the hand, however, rises too high and goes above the chin, we can speak of the hand as an arrogant dragon, and the movement becomes stiff and ungraceful. "Nine at the top means: Arrogant dragon will have cause to repent." Thus, Push Up reaches its end at the chin, or fifth place, and from there the new form begins.' Moving on, for Pull Back, Da Liu gives the trigam as K'un: 'The trigram K'un, the Receptive, characterises Pull Back. The player's hands move downward from his upper right side to his lower left. The opening words of the Great Commentary of the I Ching are appropriate: "Heaven is high, the earth is low".' Also, to give a final example, for Press Forward, he provides the trigram K'an: 'This movement, related to the trigram K'an, finds the left hand placed on the right wrist, both hands positioned close to the chest. The hands then press forward, representing the new moon waxing to the full. But in the flow of nature, when the moon is full it begins to wane. The player then separates his hands and rests backward, indicating the waning moon.' His analysis proceeds further in this way, and as I have said, I have just given a few examples to give a flavour of the book. I agree with others here that relating postures to hexagrams, trigrams and elements probably doesn't contribute a great deal in tangible terms to ones practice, but I think that having an awareness of these correspondences, even if they do differ from one Master to another, can contribute to ones form practice a certain feeling of connection with very ancient traditions and wisdom, which gives an added pleasure of its own to practising the form. Kind regards, Simon.