A sovereign attacks a Nation, either to obtain something to which he lays claim or to punish the Nation for an injury he has received from it or to forestall an injury which it is about to inflict upon him, and avert a danger which seems to threaten him . . .. Must we await the danger? Must we let the storm gather strength when it might be scattered at its rising? Must we suffer a neighboring State to grow in power and await quietly until it is ready to enslave us? . . . Supposing . . . that no injury has been received from that State, we must have reason to think ourselves threatened with one before we may legitimately take up arms. Now, power alone does not constitute a threat of injury; the will to injure must accompany the power . . . But the two are not necessarily inseparable; . . . As soon as a State has given evidence of injustice, greed, pride, ambition, or a desire of domineering over its neighbors, it becomes an object of suspicion which they must guard against . . . and, if I may borrow a geometrical expression, one is justified in forestalling a danger in direct ratio to the degree of probability attending it, and to the seriousness of the evil with which one is threatened.