The world we live in is made up of matter, and all matter obeys the laws of physics, including the characteristics of motion, including gravity and so on. However, there is a kind of immaterial existence, which enables matter to actively resist the laws of physics and make matter have life. This existence is the aura.
When your fingers hit the keyboard, do you think this action is amazing? Your hand doesn't fall on the keyboard because of the gravity of the earth, but a force is generated out of thin air, which controls your hand, makes it fall on a key accurately, and then bounces quickly. Although you can think that this is controlled by the brain, the brain itself is also a substance. If you suddenly die, your body will become a pile of substances, and your weight will not be less, but the aura will dissipate. Without this pile of substances, this kind of thing can control your body, so your body will change from a substance with aura control to a substance without aura control.
With this understanding, you should be able to feel the existence of the aura. As for absorbing reiki ... I believe that more reiki can control more substances, but the fierce ability to absorb reiki is still unknown.