For supposing we assume that some movement in the bodily organs is associated sympathetically with all our thoughts, it is readily intelligible how the sudden act above referred to, of shifting the mind now to one standpoint and now to the other, to enable it to contemplate its object, may involve a corresponding and reciprocal straining and slackening of the elastic parts of our viscera, which communicates itself to the diaphragm (and resembles that felt by ticklish people), in the course of which the lungs expel the air with rapidly succeeding interruptions, resulting in a movement beneficial to health.