I made an attempt to switch from zygote to _fill in the blank, - but of course no one will acknowledge that because it would mess up their argument. If I missed a few spots here and there - my apologies. Call it what you want - a cell, zygote, blastocyst, it still doesn’t possess person hood. We’ll just have to disagree. Aquinas is continually mined arguing the existence for god, and he didn’t believe a soul entered the fill in the blank at conception. Good for him. I’ll use him and all his greatness to back me up…

Of course though this will be explained a way somehow by someone - I’m sure very eloquently. When you believe in the supernatural you can twist anything at any given moment to support your claims. It’s awesome. He even stated that terminating a pregnancy before ensoulment while a sin -
was something less than homicide - Look at the big brain on Aquinas!!!
From a catholic website -
catholicsforchoice.org/pubs/cfc_archive/articles/TheHistoryofAbortion.asp
Most people believe that the Roman Catholic Church’s position on abortion has remained unchanged for two thousand years. Not true. Church teaching on abortion has varied continually over the course of its history.
There has been no unanimous opinion on abortion at any time. While there has been constant general agreement that abortion is almost always evil and sinful, the church has had difficulty in defining the nature of that evil. Members of the Catholic hierarchy have opposed abortion consistently as evidence of sexual sin, but they have not always seen early abortion as homicide. Contrary to conventional wisdom, the “right-to-life” argument is a relatively recent development in church teaching. The debate continues today.
St. Augustine (354-430) condemned abortion because it breaks the connection between sex and procreation.[1] However, in the Enchiridion, he says, “But who is not rather disposed to think that unformed fetuses perish like seeds which have not fructified”–clearly seeing hominization as beginning or occurring at some point after the fetus has begun to grow. He held that abortion was not an act of homicide. Most theologians of his era agreed with him.
circa 8th Century: Recognizing Women’s Circumstances
In the Penitential Ascribed by Albers to Bede, the idea of delayed hominization is again supported, and women’s circumstances acknowledged: "A mother who kills her child before the fortieth day shall do penance for one year. If it is after the child has become alive, [she shall do penance] as a murderess.
1140: Abortion of an Unformed Fetus Is Not Homicide
In 1140, Gratian compiled the first collection of canon law that was accepted as authoritative within the church. Gratian’s code included the canon Aliquando, which concluded that “abortion was homicide only when the fetus was formed.”[4] If the fetus was not yet a formed human being, abortion was not homicide.
1312: “Delayed Hominization” Confirmed
The Council of Vienne, still very influential in Catholic hierarchical teaching, confirmed the conception of man put forth by St. Thomas Aquinas. While Aquinas had opposed abortion – as a form of contraception and a sin against marriage – he had maintained that the sin in abortion was not homicide unless the fetus was ensouled, and thus, a human being.
1588: Abortion’s Penalty Becomes Excommunication
Concerned about prostitution in Rome, Pope Sixtus V issued the bull Effraenatam (Without Restraint) and applied to both contraception and abortion, at any stage of pregnancy, the penalty designated for homicide: excommunication. There was no exception for therapeutic abortion.[6]
1591: Rules Quickly Relaxed
Only three years after Pope Sixtus V issued Effraenatam, he died. His successor, Gregory XIV, felt Sixtus’s stand was too harsh and was in conflict with penitential practices and theological views on ensoulment. He issued Sedes Apostolica, which advised church officials, “where no homicide or no animated fetus is involved, not to punish more strictly than the sacred canons or civil legislation does.”[7] This papal pronouncement lasted until 1869.