Lena had accepted Timothy as an illegal student of sorts, and she was about to teach him the basics of Phantom Alchemy! This branch of magic was very important, but it also required a set of skills and intelligence that most people, or entities, did not possess, so if Timothy even had the slightest chance to understand this craft, he had to start with the basics! Knowledge was one of the most valuable aspects of this craft.
“First, you have to understand what souls are made of, Timothy. See when your soul is in your body, it's massless, almost insignificant, as it's attached somewhere between your conscious, and subconscious, deep inside your brain. However, when you choose to use any form of magic that separates your soul from your body, your soul can't be massless any longer, it turns into gas.” Lena explained.
“Yeah, I've picked up on that. Since oxygen is also a type of gas, does that mean that my soul is currently made out of oxygen, amongst other gases?” He followed along.