By the way, a very important bit of physical education for a child is to train in him a sensitive nose – nostrils which sniff out the least ‘stuffiness’ in a room, or the faintest odour attached to clothes or furniture. The sense of smell appears to have been given us not only as an avenue of pleasure, but as a sort of danger-signal to warn us of the presence of noxious matters: yet many people appear to go through the world without a nose at all; and the fact tends to show that a quick sense of smell is a matter of education and habit. The habit is easily formed. Encourage the children to notice whether the room they enter ‘smells’ quite fresh when they come in out of the open air, to observe the difference between the air of the town and the fresher air beyond; and train them to perceive the faintest trace of pleasant or harmless odours.