The Immaculate Conception and the evolution of dogma

Despite the fact that the belief in Mary’s immaculate conception has been a dogma since 1854, many people still don’t understand what it means. Maybe it’s because it took so long for the Church to fully understand this teaching. In a recent

St. Thomas on Mary

Question: I recently read that St. Thomas Aquinas was among those opposed to the Immaculate Conception. How do we square his status as one of the great minds of the Church with this now being an infallibly defined dogma? — Dick Jones,