 By the early 16th century the hopes of the concept becoming Catholic doctrine had receded, and have never seriously revived.A number of theologians have discussed the concept over the years, from the 19th-century Father Frederick William Faber, to the 20th-century Mariologist Father Gabriel Roschini.In his 1946 publication "Compendium Mariologiae", Roschini explained that Mary did not only participate in the birth of the physical Jesus, but, with conception, she entered with him into a spiritual union.