What is the justification for transubstantiation?

Transubstantiation is a belief held by some Christian denominations that during the Eucharist, the bread and wine actually transform into the body and blood of Jesus Christ while retaining the appearance of bread and wine. The justification for transubstantiation comes from interpretations of passages in The Bible, particularly the Last Supper accounts in the Gospels, and teachings of early Church fathers such as St. Augustine and St. Thomas Aquinas. The belief is seen as a way to uphold the real presence of Christ in the Eucharist.