Weakness

As the Nobility was fated to live by night alone, electronic protection
during the day was an absolute necessity. No matter how much mysticmight the vampires might wield by night, in the light of day they were
feeble creatures, easily destroyed by a single thrust of a stake. It was for
precisely this reason that the vampires had used all their knowledge of
psychology and cerebral biology in their attempts to plant fear in the human
mind throughout the six or seven millennia of their reign.

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