""Discretion" means, when it is said that something is to be done within the discretion of the authorities that that something is to be done according to the rules of reason and justice, not according to private opinion; according to law and not humour. It is to be not arbitrary, vague, and fanciful, but legal and regular. And it must be exercised within the limit, to which an honest man, competent to the discharge of his office, ought to confine himself."