Reasons for opposing the traducianism of human beings include the metaphysical argument that since humans cannot control their own existence, their existence cannot be caused by themselves; it must rather be caused by a necessary being otherwise known as God. Creation, in other words, includes God's on-going causation of human existence. This causation is through the human soul because, as Saint Thomas Aquinas argues, the human Soul has activities beyond the capacity of matter and the existence of these activities shows that the human soul is both immaterial and immortal---but not independent of God's causality. The Roman Catholic Church teaches that "every spiritual soul is created immediately by God - it is not "produced" by the parents, and also that it is immortal..." Humans have, however, free will and thus control over their own existence, as much as they are responsible for the act of procreation.