The Biology of Cell
Perhaps the simplest and therefore most elegant definition of biology is that it is the science of how cells communicate with each other. How does it happen that the abstract concept of "duty" originating in our mind results in the actual movement of first one leg and then another out of a warm bed and onto a cold floor? What, physiologically, takes place when an acute, painful sensation in a man's chest produces the abstract mental image of the number 911, to call for an ambulance? How can a dream image of a ferocious lion produce a rise in blood pressure and rapid heart beat? In other words, what we would like to explain is how, for example, the concept of work as God-pleasing activity, toil, torture, or whatever, can be translated from an image in the brain—a concept—to a set of actions on the part of the foot, resulting in our getting out of bed on a cold, rainy morning. Conversely, physiological messages from the toe can reach the brain and produce images, thoughts, and feelings of such complexity as, for example, to go searching for a pair of nail clippers to alleviate the pain from an ingrown toenail. Without connections between the brain, mind, and the rest of the body, multicellular organisms could not exist.
What we call mental or emotional processes, thoughts, feelings, affects, and images, are physical events. Otherwise they