The extracellular membrane selectively filters a cell’s environment, actively or passively transmitting some molecules into the cell, responding to others, and excluding many. And it retains the cell’s contents. Environment and heredity are thus connected by the membrane. “The true secret of life lies in understanding the elegantly simple biological mechanisms of the magical membrane—the mechanisms by which your body translates environmental signals into behavior”. And “It is a single cell’s “awareness” of the environment, not its genes, that sets into motion the mechanisms of life.”43