the.com/inside
Where the walls are, the secrets live, and the weather can't reach you.
means The interior of something — physically, or the private knowledge and feelings hidden from outsiders.
from Plain Old English logic: in plus side, the side that faces in, recorded since the 1300s and never overthinking it.
Prison slangInside means behind bars since the 1800s.
Inside jobCrime committed by someone trusted, not a stranger.
Inside outKnowing something so well its seams show.