Dimension
A dimension is an order of relationship governed by characteristic conditions and constraint. It determines what kinds of location, movement, interval, form, sequence, perception and interaction can occur. Many frequencies and harmonics may operate within one dimensional condition.
Density
Density concerns how concentrated, resistant or constrained expression becomes. It is not a synonym for dimension, spiritual maturity or moral value. Dense material embodiment may coexist with subtle readability and developed coherence.
Octave and harmonic
An octave is a bandwidth of coherent organisation that a node or field can stably hold. A harmonic is a proportional relation stabilised within that bandwidth. Codex development uses nested scales: primary octave, developmental sub-octaves, an 8/1 threshold, stabilising harmonics, and phases of initiation, consolidation and reintegration.
The controlling distinction
Octave development is not automatically movement from 3D into 4D or 5D. A human may develop harmonically while remaining physically embodied within Gaia’s material order. Subtle access does not by itself prove a dimensional relocation.