What is less well known is that many of Nostradamus's other predictions in his "Propheties" and accompanying letters are clearly based directly on ancient collections of prophecies that were similarly known and available long before he started writing. Numerous such collections were being made at the time, the first and best known of these anthologies to be published in France was the celebrated Mirabilis liber, an early 16th-century collection of prophecies mainly in Latin, though partly in French .