I need to deal with this difference more specifically later. At this point I need to say only that we humans differ in having three levels of mind or three levels of understanding and will, and that these levels can be opened in sequence. Since they are translucent, we can be raised in understanding into heaven’s light and see things that are not only civically and morally true but spiritually true as well. Once we have seen many such truths, we can on that basis draw a series of true conclusions, and keep perfecting our understanding in this way forever.
Animals, though, do not have the two higher levels, only the earthly levels, and apart from the higher levels the earthly levels have no ability to think about any civic, moral, or spiritual issue. Further, since these earthly levels cannot be opened and therefore raised into higher light, animals cannot think in sequential order. They can think only in a simultaneous pattern, and that is not really thinking. It is simply acting on the basis of the knowledge that answers to their love; and since they cannot think analytically or survey their lower thought from any higher vantage point, they cannot talk. All they can do is make sounds that suit their love’s knowledge.
The only difference between sense-centered people (the lowest of the earthly-minded) and animals is that they can fill their minds with information and think and talk on that basis. They get this from an ability we all possess, our ability to understand what is true if we want to. This ability makes the difference. However, many people have made themselves lower than animals by their abuse of this ability.
from Regeneration, Pages 110-111