Be forewarned, I can still taste the ferment on my teeth. Conjecture and abstract thought do not, admittedly, serve much purpose in a guide to the mysterious world you and I now inhabit, yet I would submit that you can cut as deep as you like as long as your implement remains sharp.

Music in Book 3, Chapter 16:

Cullah - Please Bring Me Shelter (CC BY-SA 4.0)
Allen Masterton - Berceus
Scott Holmes - Abandoned City (CC BY 4.0)
Scott Holmes - Vasky Skyline (CC BY 4.0)
Blue Dot Sessions - Nervous Whisp (CC BY-NC 4.0)
Allen Masterton - Iridian
Blue Dot Sessions - Cobweb Transit (CC BY-NC 4.0)
Blue Dot Sessions - Stillness (CC BY-NC 4.0)
Crowander - Backward (CC BY-NC 4.0)
Origamibiro - Flicker (CC BY-NC-SA 3.0 US)
Crowander - Above Us (CC BY-NC 4.0)