If you are referring to the rubbing of water on her face (mud), it sounds strange, but it was the beginning of the healing waters of Lourdes. I think Lourdes is one of only a few apparitions the Church requires belief. Usually, she doesn't say. Even Medjorge is up in the air. the Church is extremely cautious about "approving" apparitions. But if you don't want to believe, it isn't necessary for Salvation. Just belief in Jesus, God, and His holy church. And Scripture too.
At the heart of the unbelief is the Immaculate conception. If you believe that Jesus is God, then Mary had to be preserved from the stain of original sin top carry God within her body. It makes sense, but was only instituted in 1853 or 1854. That's a long time coming considering she was proclaimed tyo be Mother of God in the 4 th century.
But I'm preaching. I was an atheist for 18 years. Then my eyes were reopened. Back to Nostradamus, he himself was a convert. He knew the end. And he knew more physics than we know today.
Yes that's correct the whole mud story the white lady told Bernadette to do as an act of penance, and the chapel story that had to be build. As far as I can read Bernadette never claimed she saw Mary and Bernadette also seemed to have said herself that it is not the water doing the healing but just your own prayers. Bernadette did not like all the attention of all the other people. Poor girl who was just psychic like Nostradamus and millions of other people in the world.