"And I might add the confidence with which distracted persons do oftentimes, when they are awake, think, they see black fiends in places, where there is no black object in sight without them"

This quote by Robert Boyle is referring to the power of the imagination and how it can develop illusions. He is suggesting that when individuals are in a state of distress, they can frequently envision seeing things that are not actually there. This might be interpreted as a warning versus permitting our creativities to cut loose and to be mindful of the power of our ideas. He is also suggesting that our minds can be so effective that they can create impressions that appear real, even when there is no physical object present. This quote is a reminder to be familiar with our thoughts and to be conscious of how our imaginations can affect our understanding of reality.