And all of them help to foster the spiritual and psychological growth that sometimes allows us to develop hope, faith, and gratitude even late in life. First, dreaming, by allowing us, in our minds, to manipulate past and future, gives us a way to master the passage of time. As egg-laying mammals like echidnas and platypuses evolved from their reptilian ancestors, they developed dramatically enlarged frontal lobes, but not the capacity to dream. Such expansion of the frontal lobes is thought to reflect an increased capacity to associate, to comprehend, and to reflect prior to action. Humans have evolved both the hypertrophied frontal lobes shared with more primitive mammals and the capacity to dream at night shared with dogs and cats.
Humans also have the capacity to rehearse both past and future through daydreams while awake.
Daydreaming and, by inference, night dreaming allow us to re-create the past and to rehearse the future. Thus, the evolution of both dreaming and the associational areas of the frontal lobes allows the organism to link past experience to future choice. Perhaps imagination and daydreaming are the same thing - but they are essential to the mastery of time, to the development of mature defenses, and to wondering whence we come and wither we are going. Dreaming and the frontal lobes permit us to imagine, and imagination is essential to religion, psychotherapy, and mature defenses. Without imagination and the capacity to transcend time present, mature defenses and faith would be impossible.