Elizabeth, with a countenance of grave reflection, soon after they were seated at table: "This is a most unfortunate affair, and will probably be much talked of. But we must stem the tide of malice, and pour into the wounded bosoms of each other the balm of sisterly consolation." Then, perceiving in Elizabeth no inclination of replying, she added, "Unhappy as the event must be for Lydia, we may draw from it this useful lesson: that loss of virtue in a female is irretrievable; that one false step involves her in endless ruin; that her reputation is no less brittle than it is beautiful; and that she cannot be too much guarded in her behaviour towards the undeserving of the other sex." Elizabeth lifted up her eyes in amazement, but was too much oppressed to make any reply. Mary, however, continued to console herself with such kind of moral extractions from the evil before them. In the afternoon, the two elder Miss Bennets were able to be for half-an-hour by
comes first. What need for cryptography if no one would eavesdrop? Why build forts if no one would attack? Thus the assumption that someone will attempt a cryptanalysis, no matter how tentatively or incompetently, engenders cryptography. Experience of the interreaction between cryptography and cryptanalysis has precipitated out certain practical principles. They all refer to time, because all practical matters involving mortal men connect eventually with that one inexorable, irreversible, irretrievable factor. Time, for the cryptographer, controls a variable relationship. The most general of the cryptographer's principles deals with the sliding ratio between speed and security; as the need for speed in communications increases, the need for security decreases. Early in the planning of a major operation, messages demand great security because the enemy, if he could read them, would have time to prepare countermoves. But in the heat of battle, commanders may use plain language because the
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