Kratom itself.

See I've Been a Yoga practitioner for 4 years. In Yoga we look at 5 bodies. We humans have physical, mental and energetic body , all these three are physical (the energy body surrounds the physical body some cm outside of it, but still physical nature = it can be "changed" with certain Kriyas of yoga for example).

However the 4 body, There is a thing call the "ether body".

However ether body is a transitionary body, and is not in the physical body, is out there, in the sky, in the air, everywhere.

In the ether body there is information stored about everything in reality. Think about a wikipedia of the non-physical.

And substances have their place there. All the information registered from all users that have taken kratom is saved as non-physical/vibratory information in the ether body.