As scientists plumb the depths of the cell, they must be particularly cognizant of the potentially harmful uses of their work, in addition to all its intended benefits. For example, knowledge of how to generate specific strings of nucleotides with high precision greatly aids research by providing particular and accurate DNA sequences with which scientists can assess cell functioning and design new living systems. But such knowledge can also produce the raw materials for building known pathogens from scratch, as has already been done (for research purposes) with the polio virus and the Spanish flu virus. As scientists develop ways to generate sequences of base-pairs ever more cheaply and efficiently, the opportunity for the malicious or the simply unreflective to play with pathogens to see what kind of traits arise looms larger. And it is not just technological know-how that can be problematic. The detailed knowledge of cellular or genetic functioning can have worrisome implications as well. Knowledge of what makes a virus more transmissible can assist us in detecting when a virus might be more prone to producing an epidemic, but it could also be used to make viruses more virulent.