Post-1970 — The first five principles are in the 1970 book (five-principles-cyclic-model). The three below appear in the Cycles Course and Hickson tradition.
The five from the book (summary)
See five-principles-cyclic-model — Summation, Commonality, Variation, Nominality, Proportionality.
6. Harmonicity
Nominal cycle wavelengths stand in simple harmonic ratios (half, double, triple). The 18-year → 5-day model is a harmonic scale. See hurst-nominal-cycles.
7. Synchronicity
Troughs of components tend to align in time. Peaks may be offset (time translation). Phasing analysis builds from synchronized troughs.
8. Cyclicality
Cycles influence price toward peaks and troughs. A cycle does not vanish when the chart looks random — it is overwhelmed by a longer dominant component.