A rich man cannot enjoy a sound mind nor a sound body without exercise and abstinence; and yet these are truly the worst ingredients of poverty.
A man who is 'of sound mind' is one who keeps the inner madman under lock and key.
A sound mind in a sound body, is a short, but full description of a happy state in this World: he that has these two, has little more to wish for; and he that wants either of them, will be little the better for anything else.