There is a frontier where virtue and vice fade into each other.
Who has ever been able to define the exact boundary between courage and rashness, between prudence and cowardice, between frugality and avarice, between liberality and prodigality?
Who has ever been able to say how far mercy to offenders ought to be carried, and where it ceases to deserve the name of mercy and becomes a pernicious weakness?
What casuist, what lawyer, has ever been able nicely to mark the limits of the right of selfdefence?
All our jurists bold that a certain quantity of risk to life or limb justifies a man in shooting or stabbing an assailant: but they have long given up in despair the attempt to describe, in precise words, that quantity of risk.

They only say that it must be, not a slight risk, but a risk such as would cause serious apprehension to a man of firm mind; and who will undertake to say what is the precise amount of apprehension which deserves to be called serious, or what is the precise texture of mind which deserves to be called firm.

It is doubtless to be regretted that the nature of words and the nature of things do not admit of more accurate legislation: nor can it be denied that wrong will often be done when men are judges in their own cause, and proceed instantly to execute their own judgment.
Yet who would, on that account, interdict all selfdefence?
The right which a people has to resist a bad government bears a close analogy to the right which an individual, in the absence of legal protection, has to slay an assailant.

In both cases the evil must be grave.

In both cases all regular and peaceable modes of defence must be exhausted before the aggrieved party resorts to extremities.