Determining the Five Elements attribute of every kind of herb was not something that could be accomplished in a moment, or even in a few years. Only through slow exploration over an extremely long time could it succeed.
As for why herbs that should inherently possess a Wood attribute could have Five Elements attributes, Zhang Xiaohua had faintly formed some ideas. Take Crimson Flame Grass, for example. Its color was red, and no plants grew around where it grew; even the soil turned to stone. Needless to say, it was Fire attribute. The two main ingredients of the Crimson Flame Pill, Crimson Pearl Grass and the Fire-attribute Crimson Flame Grass, complemented one another. Crimson Pearl Grass was surely Water attribute.
Of course, there were many more herbs whose attributes could not be seen directly from their appearance, making it impossible to directly define their Five Elements attributes.
Immortal Path Qi Practitioners possessed vast supernatural abilities and encountered far more herbs than martial artists did. If one did not use unique mystical arts and instead relied only on a method as clumsy and foolish as Zhang Xiaohua's, who knew when one would finally distinguish them clearly?
Why, then, could the art of medicine distinguish the attributes of dried herbs so clearly? First, the varieties of herbs were limited. Second, people fell ill every day, and with such extensive practice, results came easily. Even so, the art of medicine had taken several thousand years to reach its present scale.
Zhang Xiaohua engraved the pill formula and his own insights into a jade slip. After expending some divine sense, he put the jade slip away and began practicing the Spirit Guiding Technique.
Ever since he had begun using divine sense to write on jade slips, Zhang Xiaohua had understood that in the Immortal