It is also important to know that there are three levels of love and wisdom, and therefore there are three levels of life. The human mind is formed into areas that go with these levels. The life in the highest area of the mind is the highest level of life. The life in the middle area of the mind is a lesser level of life. The life in the lowest area of the mind is the lowest level of life.
These areas in us are opened one after the other. The lowest area of the mind, where there is the lowest level of life, is opened during childhood and adolescence, by means of factual information. The second area of the mind, where there is a greater level of life, is opened during adolescence and early adulthood, by means of thought that builds on factual information. The highest area of the mind, where there is the highest level of life, is opened during early adulthood, middle age, and beyond, by means of perceiving both moral and spiritual truths.
Another important thing to know is that life in its greatest perfection is not thinking; it is perceiving truth in the light of truth. The level of this perception in people can be used to determine what level of life they have. For example, there are people who, immediately upon hearing something true, perceive the truth of it. In the spiritual world they are represented as eagles. Then there are people who do not perceive what is true, but they do arrive at truth from argumentation based on other things that are apparent. They are represented as songbirds. There are people who believe something to be true because it was decreed by a man in authority. They are represented as jays or magpies.
There are also some who are unwilling and others who are unable to perceive what is true; they can perceive only what is false. The reason is that the light they are in is faint and deceptive. In that light what is false seems true, and what is true seems like something hidden in a thick cloud overhead or like a shooting star; or else it just seems false. Such people’s thoughts are represented as night birds, and their speaking as screech owls. Those among them who have become adamant in their own false impressions cannot stand to hear things that are true. As soon as anything true reaches the outermost part of their ear, they reject it in disgust much the way a nauseous stomach distended with bile will regurgitate food.
from True Christianity, Section 42