St. Thomas Aquinas
“The accidents continue in this sacrament without a subject. This can be done by Divine power: for since an effect depends more upon the first cause than on the second, God Who is the first cause both of substance and accident, can by His unlimited power preserve an accident in existence when the substance is withdrawn whereby it was preserved in existence as by its proper cause, just as without natural causes He can produce other effects of natural causes, even as He formed a human body in the Virgin’s womb, ‘without the seed of man’.”
Source: St. Thomas Aquinas, Summa Theologica