Hexagram #18 is called Corruption, Decay, or “Work on that which is spoiled. It is the visual inverse of the previous hexagram. While it is, on the surface, not a positive hexagram, it highlights the very nature of change that it contains within in a positive possibility. This hexagram points to a time of corruption or decay, and challenges you to find the source of this corruption. If you search it out and change it, you will meet with success and this will be a time of a new beginning.
The trigrams that make up this hexagram are wind under the mountain. This implies something that blocks the flow, perhaps turning it back on itself. The nuclear hexagram is #54, Converting the Maiden. This suggests that by finding the source of the corruption and dealing with it, you have the possibility of realizing your potential.
The first changing line tells you that you are dealing with a corruption of authority, and your best course of action is to make a change. The second changing line says that you are dealing with a corruption of nourishment, and you will not be able to see a way forward at this time. The third changing line tells you, once again, that you are dealing with a corruption of authority, and warns that if you are not strong you will make a serious mistake. The fourth changing line warns you that your actions are only adding to the corruption of authority. The fifth changing line still speaks of a corruption of authority, and says that you cannot attack it directly at this time. The final changing line encourages you to not mire yourself in the mundane, but to find what is beautiful in the world.