Unlike the secret-art images in the treasures he had found before, the images in the tenth secret realm were not fixed. Aside from the initial "Chaos at the Dawn of Creation" and "Condensing the Sun into the Moon," all the others varied. In particular, the secret arts displayed by the Natal Dan Artifacts were different in almost every image.
Ling Tian was quite pleased by this. From the techniques shown by the Natal Dan Artifacts in the images, he could infer many ways to use his own Natal Dan Artifact. He had gained quite a lot.
However, he still didn't understand what purpose the clouds, sun, moon, and stars served. The images hadn't shown it yet. Still, he didn't believe the Lord of the Universe would add decorations with no real use, and he had his own guesses.
Taking Po Qiong's advice, Ling Tian continued watching the images. He watched for several years.
Over those years, Ling Tian viewed thousands upon thousands of images and learned even more techniques. He also discovered what the clouds, sun, moon, and stars were for.
Just as he had guessed, the sun and moon could not only help cast yin- and yang-attribute Dao arts, but could also be combined with illusions and other secret arts. The moon in particular could be used to cast Moon Illusion Technique, just like in Fairy Silver Fox's secret realm. It simply lacked the Moon Guardian secret art.
Besides that, the energy contained in sunlight could be infused into various objects below. For instance, yang and fire attributes could be fused into a volcano, making fire-attribute Dao arts cast that way even more terrifying. The yang attribute could also be infused into trees, its gentle energy helping them grow.
Likewise, the Power of Life and Death contained in moonlight