In writing notes and comments on the Zhouyi, the author would have to make an assumption that those Yi aficionados reading the blog would have acquired a minimum of ten years reading the Book of Changes and also own a copy of the Richard Wilhelm translation. However not all readers would fall under the categories of a minimal ten years of study and/or owning a W/B translation, therefore one has to summarize the Ten Wings for fellow students who would like to know more about the technical aspects of Yi studies, and/or about the Ten Wings.
"In the Wilhelm/ Baynes English translation, Richard Wilhelm explained in Book II – The Material – that The Book of Changes is a work that represents thousands of years of slow prolonged reflection and meditation. The material presented in the second portion of their translation consists chiefly of what has come to be known as the Ten Wings. These ten wings, or expositions, contain in substance the oldest commentary literature relating to the Book of Changes.
The first of the commentaries – the First and Second Wings – is called Tuan Zhuan. The Tuan Zhuan or Commentary on the Decision gives exact interpretations of King Wen’s decisions (judgments), on the basis of the structure and the other elements of the hexagrams. This commentary (made available under individual hexagrams in Book III) is an extremely thorough and valuable piece of work and throws much light upon the inner organization of the hexagrams of the I Ching. The Chinese ascribed it to Confucius.
The Third and Fourth Wings are formed by the so-called Xiang Zhuan, Commentary on the Images. In its present form it consists of the so-called Great Images (Da Xiang), which refer to the images associated with the two trigrams in each hexagram; from these the commentary in each case deduces the meaning of the hexagram as a whole, and from this contemplation in turn draws conclusions applicable to the life of man. Besides the Great Images, this commentary contains also the Small Images. These are very brief references to the Duke of Zhou’s comments on the individual lines of the hexagrams.
The Fifth and Six Wings constitute a treatise that presents many difficulties. It is entitled Hsi Tzu, or Da Zhuan, and likewise has two parts. The title Da Zhuan means Great Commentary, or Great Treatise.
The Seventh Wing, named Wen Yen (Commentary on the Words of the Text), is a very important section. It is the remnant of a commentary on the Book of Changes – or rather of a whole series of such commentaries – and contains very valuable material deriving from the Confucian school. Unfortunately it does not go beyond the second hexagram, Kun.
The Eighth Wing, Shuo Kua, Discussion of the Trigrams, contains material of great antiquity in explanation of the eight primary trigrams.
The Ninth Wing, Hsu Kua, the Sequence – or Order – of the Hexagrams, offers a rather unconvincing explanation of the present sequence of the hexagrams. It is interesting only because the names of the hexagrams are sometimes given peculiar interpretations that are undoubtedly based on ancient tradition.
The last (Tenth) wing, Tsa Kua, Miscellaneous Notes on the Hexagrams, is made up of definitions of the hexagrams in mnemonics verses, for the most part contrasting them in pairs. "
Still, I would suggest that students should only delve deeper into the Ten Wings (mainly made available in Books II and III of the W/B translation) after a minimum ten years of Yi studies otherwise they could be confused.