Alluding to Wisdom 9: 15, Grosseteste holds the intellective power is sick because it is darkened and weighed down by the corrupt body. He intimates that human beings are born in this condition, presumably as a consequence of the fall. He likens this darkening of the mind to a cloudy day: as bodily vision is darkened by clouds, so the operation of the cognitive powers is darkened by bodily appearances (phantasmata), which obstruct our mental vision and render it unable to see intelligible items in their purity. This darkening of the mind, Grosseteste holds, is the source of all error. In grasping the principles of demonstration, reason is stimulated to leave this darkness. In a newborn human being the powers of the rational soul are as if asleep and unable to act. But sense experience in some way involves reason, and through repeated sense experience reason is woken up and carried by the senses to perceptible things. Reason then begins to distinguish and view apart the features confused in sense experience, thereby formulating universal concepts. Repeated experience of correlated perceptible phenomena leads the senses to estimate an imperceptible relationship between them—a causal connection, for example. This too awakens reason and leads it to wonder whether this connection in fact obtains. Grosseteste uses an example, drawn from Avicenna, of the claim that scammony of itself causes the discharge of red bile. Wondering whether this is true, we set up what we should now call a controlled experiment in which we exclude other known causes of the discharge of red bile and give someone scammony to see what will happen. And in this way, Grosseteste writes, we arrive “from sense at an observational (experimentale) universal principle” (Rossi 1981, 215).