Extensive quantitative experiments on the model bacterium E. coli have established that many bacterial behaviors are organized in simple manners in accordance to the rate of cell growth. The existence of these simple empirical relations (growth laws) despite myriads of complex biomolecular interactions suggests a tremendous degree of "dimensional reduction" occurring in living cells, reminiscent of dimension reduction in thermodynamics, whereby e.g., the behavior of gas particles interacting via complex inter-molecular forces is captured by the ideal gas law.  In this talk, I will describe how the bacterial growth laws can be used to make accurate predictions of cell behaviors, and discuss how the magic of dimensional reduction can be accomplished by cells through clever strategies of molecular signaling.