The reason for such a situation was actually very simple. There were many meridians in the human body, including 12 regular meridians, 8 extraordinary meridians, and some sunken meridians. As of now, there was no cultivation method that could cultivate all the meridians in the human body. However, if one could not cultivate all the meridians in one's body, it would have a great impact on one's cultivation. This wooden barrel was made of many wooden boards, which were equivalent to the meridians in one's body. The meridians that had been cultivated were naturally wider and tougher, like a long wooden board. The meridians that had not been cultivated were relatively smaller and tougher, like a short wooden board. How strong you were was equivalent to how much water you could hold in your wooden bucket. Everyone knew that the amount of water a wooden bucket could hold was not determined by the longest wooden board, but by the shortest one.