When you cast and you need to read from the hexagram. Which line is revealing your answer? Just like you need to search a document and you not sure where is it, how do you start the searching? If you think that the document is in your house, room 3. Then you start to search from room 3 and scale up from there. So, this room 3 is the place you search from your answer and everything scale up from here. This is the equivalent to the matter-element. The so-called useful element is the answer that you looking for from the hexagram.
Majority of the people who learn or apply King Wen Oracle calls this "matter-element" as "useful-spirits". It is an interpretation literary from the mandarin word, 用神. However, the genuine definition for the useful-spirits is not what most of the people are understanding.
In this video, I will explain the cycle of the matter-element which is the source element 元神, dreadful element 忌神, revenging element 仇神, and free element 閒神. This is only an initial concept for you to get the entry ticket into the King Wen Oracle. I have to make things clear here, the original framework for the useful-spirits cycle is not the same as I am explaining in this video.
In this video, I also explain the theory about weather prediction with the King Wen Oracle. So that you can try on your own now.