This is an embarrassing episode, for the Church to approve an apparition and then have to go on and place the seer on the index. Perhaps the Church should wait until the visionary is dead before approving an apparition. I have always been confused by this myself and it seems like it would be sinful to spread this message that was later published by Melanie and it has been widely spread. What on earth did the Blessed Virgin tell in secret that did not appear to help the Church to avoid a devastating crisis anyway? So weird. I also read a bunch of that book Satanism a Social Hx and it does seem to me that Diana Vaughan was completely made up for a troll and that they trolled St. Therese of Lisieux, which is absolutely horrible.
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Oh, I don't know if it's embarrassing to the Church. Our Lady and appeared to Melanie and told her to tell the world to stop violating the Sunday and stop taking God's name in vain. The Church approved of this, and it was all good. If Melanie went off the reservation later in her life, that's on her. My understanding is that the secret of La Salette was intended to be a private message to Pope Pius IX, and was never intended to be published. If you think about it, any pope since Pius IX could have published that text, but they all chose not to, and we've had some pretty amazing popes in that time period, including Pius IX himself. The idea that he would have been afraid to publish anything he should have published is absolutely laughable. So if he didn't publish it, that means it probably wasn't supposed to be published.
I will admit, though, that this is certainly a bizarre and unique event in the history of the Church, as far as I know. Most seers are holy people, and usually canonized saints -- St. Margaret Mary, St. Bernadette Soubirous, St. Catherine Labore, etc. Even in cases where they aren't canonized, such as Juan Diego or the three children of Fatima, they are still pious people of unimpeachable reputation. Melanie is the only person I've ever heard of who had an approved apparition and then wrote a text that the Church put on the Index.