We sympathize with the sufferer and that means that the pain which he expresses becomes our own pain.

We share the joy of the happy lover and the grief of the despondent mourner, we feel the indignation of the betrayed wife and the fear of the man in danger.

The visual perception of the various forms of expression of these emotions fuses in our mind with the conscious awareness of the emotion expressed; we feel as if we were directly seeing and observing the emotion itself.

Moreover the idea awakens in us the appropriate reactions.

The horror which we see makes us really shrink, the happiness which we witness makes us relax, the pain which we observe brings contractions in our muscles; and all the resulting sensations from muscles, joints, tendons, from skin and viscera, from blood circulation and breathing, give the color of living experience to the emotional reflection in our mind.