WHAT DREAMS ARE MADE OF. -71 



which is credited with being the scene of a never-ending bustle and 

 traffic in ideas, the heart may be thought of as an organ whose duties 

 permit of no cessation or repose. Even in the ordinary undisturbed 

 performance of its functions, the rhythmical routine of the great 

 pumping-engine strikes us as resembling that of the galley-slave 

 chained to the oar, and as exhibiting day by day the same unflagging, 

 stereotyped way of life and action. The question of rest for such an 

 organ might at first sight appear non-existent. Its nutrition likewise 

 would seem to be a matter in arranging for which, conformably with 

 its perpetual round of duties, nature might experience some difficulty; 

 since, like the through railway guard on an extended journey, it must 

 feed as it runs. 



But the dilemma in question is solved through the simple con- 

 sideration of the manner in which the heart's work is performed. 

 The action of the organ, as every one knows, is not continuous. Its 

 work is intermittent in character, as may be proved by listening to 

 the sounds it makes. It has its periods of repose, short as these may 

 be, between its strokes of work. It takes its rest in short alternate 

 naps ; and if we sum up its life history, and calculate its working hours, 

 we shall find that, in truth, the heart has rested for a longer period 

 than it has worked. Thus although the snatches of rest be short, in 

 the case of the heart they are really as frequent as its working moments, 

 and in the intervals betwixt its pulsations it may be said to gather 

 energy for its succeeding strokes. The case of the muscles used in 

 breathing and it may be borne in mind that the heart itself is 

 simply a hollow muscle is equally interesting, and certainly not less 

 typical than that of the central organ of the circulation. The periods 

 of work, so to speak, are longer in the case of the chest-muscles, 

 just as the intervals of repose are more protracted than in the 

 business of the circulation. And if the idea of rest alternating with 

 work be extended to other departments of bodily activity, we shall 

 find that the practice in question prevails throughout the living 

 organism. The chief differences between the action of one set of 

 muscles and that of another set consist in the varying duration and 

 succession of the periods of work and rest. In absolute cessation from 

 labour, then, we find a profitable source of repair of the body. Then 

 it is that the materials derived from the food can be perfectly applied 

 to the necessities and wants of the frame. The true justification of 

 sleep is found after all in the value of rest as a reparative measure. 

 And the after-dinner nap of well-favoured humanity, equally with the 

 somewhat prolonged post-prandial inactivity of the boa-constrictor, 

 are procedures separated, it may be, by an infinity of differences, 

 but which, perchance, derive much of their reasonableness from the 

 physiological considerations besetting the question of repose. 



As a knowledge of the nature of sleep becomes a necessity for 



