A physicist's view on biological synergies: Comment on “Hand synergies: Integration of robotics and neuroscience for understanding the control of biological and artificial hands” by Marco Santello et al.

• Definition for a living system is offered.
• Different definitions of synergy are contrasted.
• Synergies are linked to stability of performance.
• The uncontrolled manifold and equilibrium-point hypotheses are merged into a single scheme.