You act, and feel, not according to what things are really like, but according to the image your mind holds of what they are like. You have certain mental images of yourself, your world, and the people around you, and you behave as though these images were the truth, the reality, rather than the things they represent.
Let us suppose, for example, that the man on the trail had not met a real bear, but a movie actor dressed in a bear costume. If he thought and imagined the actor to be a bear, his emotional and nervous reactions would have been exactly the same. Or let us suppose he met a large shaggy dog, which his fear-ridden imagination mistook for a bear. Again, he would react automatically to what he believed to be true concerning himself and his environ­ment.
It follows that if our ideas and mental images concern­ing ourselves are distorted or unrealistic, then our reac­tion to our environment will likewise be inappropriate.