In that sentence is the basic principle of Chiropractic.
Tone is the normal degree of nerve tension.
Tone is expressed in functions by the normal elasticity, activity, strength and excitability of the various organs, as observed in a state of health. At the Johns Hopkins School of Medicine, Donald S. Coffey and Kenneth J. Pienta found that tensegrity structures function as coupled harmonic oscillators. DNA, nuclei, cytoskeletal filaments, membrane ion channels and entire living cells and tissues exhibit characteristic resonant frequencies of vibration. Very simply, transmission of tension through a tensegrity array means to distribute forces to all interconnected elements and, at the same time, to couple, or 'tune,' the whole system mechanically as one. Tone and tensegrity are elegant theoretical models with practical clinical implications.