Although Thomas Aquinas (1224–1274) carefully and meticulously investigated what was known in general about human senses, intellect, will, and emotions, he believed that the human being is the whole of all these faculties or “powers.” Simply put, the physical body is the matter or material of a human being, and its form or soul is its “substantial form.” That the soul can understand general truths and exercise free will proves its non-materiality. The reality of the soul is its spirituality. Because the soul cannot be divided, it cannot be corrupted and is therefore immortal. Furthermore, because the soul cannot be divided, it cannot be the result of biological inheritance but is made directly by God, each time a person is born. This divine intervention at birth gives the biological process of human reproduction a dignity and sanctity that elevates the institution of marriage.