The combination of mental and physical fatigue, as it is practised in
many pursuits at this time, are exceedingly dangerous. Long journeys
each day, to and from the sphere of profession or business, are hurtful.
The idea that mental labour may be advantageously supplemented by
violent muscular exercise, such as is implied in long and fatiguing
walks or laborious exercise on horseback, is an error. Moderate and
regular exercise, at the same time, favours mental work. The practical
point is to regulate the physical labour that it shall not induce
fatigue.