WITH MUSCULAR EXERCISE. 115 



healthful results of complete cheerful exertion will 

 never be obtained where the nervous impulse which 

 animates the muscles is denied. 



It must not, however, be supposed that a walk 

 simply for the sake of exercise can never be bene- 

 ficial. If a person be thoroughly satisfied that ex- 

 ercise is requisite, and perfectly willing, or rather 

 desirous, to obey the call which demands it, he is 

 from that very circumstance in a fit state for de- 

 riving benefit from it, because the desire then be- 

 comes a sufficient nervous impulse, and one in 

 perfect harmony with the muscular action. It is 

 only where a person goes to walk, either from a 

 sense of duty or at the command of another, but 

 against his own inclination, that exercise is com- 

 paratively useless. 



The advantages of thus combining harmonious 

 mental excitement with muscular activity have not 

 escaped the sagacity of the late Dr. Armstrong, 

 who thus notices them in his frequently reprinted 

 poem on the Art of Preserving Health, but without 

 giving the physiological explanation : 



In whatever you sweat 



Indulge your taste. Some love the manly toils, 

 The tennis some, and some the graceful dance; 

 Others more hardy range the purple heath, 

 Or naked stubble, where from field to field 

 The sounding covies urge their lab'ring flight, 

 Eager amid the rising cloud to pour 

 The gun's unerring thunder ; arid there are 

 Whom still the meed of the green archer charms. 

 He chuses best whose labour entertains > <-. 



His vacant fancy most ; THE TOIL YOU HATE 

 FATIGUES YOU SOON, AND SCARCE IMPROVES YOUR LIMBS. 



Book III. 



This constitution of Nature, whereby a mental 

 impulse is required to excite and direct muscular 

 action, points to the propriety of teaching the young 

 to observe and examine the qualities and arrange- 

 ments of external objects. The most pleasing and 



