Humans experience five main types of instinct, wrote Jung: hunger, sexuality, activity, reflection, and creativity. These instincts, listed in order of increasing abstraction, elicit and constrain human behavior, but also leave room for freedom in their implementation and especially in their interplay. Even a simple hungry feeling can lead to many different responses, including metaphorical sublimation. These instincts could be compared to the "drives" discussed in psychoanalysis and other domains of psychology. Several readers of Jung have observed that in his treatment of the collective unconscious, Jung suggests an unusual mixture of primordial, "lower" forces, and spiritual, "higher" forces.