"Perfect knowledge of such things cannot be acquired without divine inspiration, given that all prophetic inspiration derives its initial origin from God Almighty, then from chance and nature. Since all these portents are produced impartially, prophecy comes to pass partly as predicted." Nostradamus
Paraphrased from the Wikipedia definition of Prophecy "Prophecy involves a process in which one or more messages allegedly communicated to, or through a prophet are then communicated to other people. A prophet's messages involve divine inspiration, interpretation, or revelation of events to come."
Nostradamus gave God and the study of the stars and their alignments to the other stars the credit for his accurate prophetic words. The Bible has a view of astrology that seems clearly opposed to astrology. So I would assume this is an area of Nostradamus using his own "interpretation." Leviticus 19:31
“So many evils by Satan's prince will be committed that almost the entire world will find itself undone and desolated. Before these events, many rare birds will cry in the air, 'Now! Now!" and sometime later will vanish”
Some argue, perhaps rightly, but not necessarily so, that the way to be accurate in prophecy is to be vague. But the real way to be accurate is to be accurate. If people can see the pieces of the prophecy message fitting the event, they can find it to be accurate.
Nostradamus might have accurately predicted:
The death of King Henry II
The great fire of London
The French Revolution
The rise of Napoleon
Louis Pasteur's Discoveries
Hitler's rise, terror, fall
The Atomic bomb