Book excerpt: The Human Person presents a brief introduction to the human mind, the soul, immortality, and free will. While delving into the thought of Thomas Aquinas, it addresses contemporary topics, such as skepticism, mechanism, animal language research, and determinism. Steven J. Jensen probes the primal questions of human nature. Are human beings free or determined? Is the capacity to reason distinctive to human beings or do animals also have some share of reason? Have animals really been taught to use language?