any way serving that agent to the furtherance of the end that he has
in view. If a visitor to a quarry were standing on a piece of rock,
which a quarryman had occasion to blast, and the man fired the train
regardless of the visitor, the latter would be _incidentally_ killed.
Now incidental killing, even of the innocent, is not under all
circumstances unlawful. Where the end in view is in the highest degree
important, the means may be taken thereto, provided always that such
an issue as the shedding of innocent blood be not itself the means
discerned and elected as furthering the end: for no end however urgent
can justify the employment of any evil means. (_Ethics_, c. iii., s.
ii., nn. 3, 13, pp. 32, 36.) Suppose in the instance just given the
quarryman saw that, unless that piece of rock where the visitor stood
were blown up instantly, a catastrophe would happen elsewhere, which
would be the death of many men, and there were no time to warn the
visitor to clear off, who could blame him if he applied the explosive?
The means of averting the catastrophe would be, not that visitor's
death, but the blowing up of the rock. The presence or absence of the
visitor, his death or escape, is all one to the end intended: it has
no bearing thereon at all.

6. We must then distinguish between _means_ and _circumstances_. The
means help to the end, the circumstances of the means do not. When the
end is of extreme urgency, circumstances may be disregarded: the means
become morally divested of them. So I have seen an island in a river,
a nucleus of rock with an environment of alluvial soil. While the
stream was flowing placidly in its usual course, the island remained
intact, both rock and earth. But when the water came rushing in a
flood, which was as though the island itself had gone speeding up the
river, the loose matter at its sides was carried away, and only the
central rock remained. The ordinary flow of the river past the island,