The main reason why our Sadhus and Fakirs are strong as a class is that they go about from one end of the country to the other only on foot. Thoreau, the great American writer, has said many remarkable things on walking as an exercise. He says that the writings of those who keep indoors and never go out into the open air, will be as weak as their bodies. Referring to his own experience, he says that all his best works were written when he was walking the most. He was such an inveterate walker that four or five hours a day was quite an ordinary thing with him! Our passion for exercise should become so strong that we cannot bring ourselves to dispense with it on any account. We hardly realise how weak and futile is our mental work when unaccompanied by hard physical exercise. Walking gives movement to every portion of the body, and ensures vigorous circulation of the blood; for, when we walk fast, fresh air is inhaled into the lungs. Then there is the inestimable joy that natural objects give us, the joy that comes from a contemplation of the beauties of nature. It is, of course, useless to walk along lanes and streets, or to take the same path every day. We should go out into the fields and forests where we can have a taste of Nature. Walking a mile or two is no walking at all; at least ten or twelve miles are necessary for exercise.