The first statement that usually accompanies a talk or journal article on cellular biology is usually something like, "Life is complicated." The apparent complexity of the networks we find in living cells is sometimes quite overwhelming. Historically, many of us have shied away from tackling system-level questions, being content instead to productively study individual proteins or genes. The new mantra, systems biology, is proclaiming a change in attitude, to convince us that this overwhelming complexity is, in fact, tractable to human understanding. As a card-carrying, bonafide systems biologist, I would have to agree.