Although Earth was more developed than Mia's world, the latter was not completely inferior to the former. It was even superior in some aspects. In the field of medicine, Mia's world, which has alchemy and restorative theurgy magic, was more advanced. On Earth, advancements in medicine solely depended on scientific breakthroughs.
With the differences in the natural laws and world systems of both worlds in mind, Baiyi decided to salvage the little time he had left before his forced emission e to select the kind of books he should rob. Hence, he discarded books on Earth's geography, history, and biology, and prioritized books on modern telecommunication and engineering. Mathematics books were also chosen, as the subject was the foundation of almost all of Earth's knowledge. Such an important subject would serve as the foothold that Mia's world needed to be revolutionalized.
