Nostradamus, Lonesome Dove, History Channel

I watched a TV program on The History Channel last night about Nostradamus.

When they were talking about the opening of his tomb, I saw a Latin phrase engraved on the stone above the doorway to his tomb.

The phrase was, “Uva uvam vivendo varia fit.”

This phrase appeared in McMurtry’s Lonesome Dove, and has puzzled many people for a long time.

I have tried to translate this phrase for years. I cannot make sense of it because it seems to be either grammatically incorrect or misspelled. It almost means “Grapes become ripe grapes by staying alive.”

Does anyone know if Nostradamus wrote the phrase?

Was this phrase commonly found on tombs in France?

Was this a private, insider’s joke by someone on the History Channel’s production team?

from http://alkek.library.txstate.edu/swwc/ld/ldex081a1.html. As to the Nostradamus thing, I don’t know.

*bolding mine–ed.