whole company in a roar of laughter, while the former would ordinarily not be regarded as worth attending to.

It is remarkable that in all such cases the jest must contain something that is capable of deceiving for a moment. Hence, when the illusion is dissipated, the mind turns back to try it once again, and thus through a rapidly alternating tension and relaxation it is jerked back and put into a state of oscillation. This, because the strain on the cord as it were is suddenly (and not gradually) relaxed, must occasion a mental movement, and an inner bodily movement harmonising therewith, which continues involuntarily and fatigues, even while cheering us (the effects of a motion conducive to health).

For if we admit that with all our thoughts is harmonically combined a