Sensation is not the conduction of a quality or state of external bodies to consciousness, but the conduction of a quality or state of our nerves to consciousness, excited by an external cause. ↗
Variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike and behave alike under the abnormal conditions which we know as disease. ↗
The realm of immediate or personal knowledge is a narrow circle in which these bodies move; the realm of knowledge derived through faith is as wide as the universe, and old as eternity. ↗