Thus considered, we may conclude that that man alone is perfectly healthy whose body is well formed, whose teeth as well as eyes and ears are in good condition, whose nose is free from dirty matter, whose skin exudes perspiration freely and without any bad smell, whose mouth is also free from bad smells, whose hands and legs perform their duty properly, who is neither too fat nor too thin, and whose mind and senses are constantly under his control. As has already been said, it is very hard to gain such health, but it is harder still to retain it, when once it has been acquired.