Drinking from a fire-hose is an old cliché for the experience of learning basic and clinical sciences in medical school, and the pipe has been growing fatter at an alarming rate. Of course, it does not stop when one graduates; if anything, both the researcher and clinician are flooded with even more information. Slightly embarrassingly, while modern science is very good at generating new information, our ability to weave multiple strands of data into a useful and coherent story lags quite far behind. Bioinformatics, systems biology and computational medicine have arisen in recent years to address just this challenge. This essay is an introduction to the problem of data synthesis and integration in biology and medicine, and how the relatively new art of biological simulation can provide a new kind of map for understanding physiology and pathology. The nascent field of computational immunology will be used for illustration, but similar trends are occurring broadly across all of biology and medicine.