This article is from the Prophecies of Nostradamus FAQ, by firstname.lastname@example.org.
The D.Cannon books I-III contain a great deal of information on
Nostradamus' techniques, which came from a variety of sources. First,
he acknowledges he was born with an inner "sixth sense", i.e. a
strong intuition and great psychic abilities. Secondly he had
enormous drive to develop it. His grandfather apparently passed him
books on witchcraft that allowed him to experiment with some rituals.
He also had access to "lost" manuscripts handed down outside of the
libraries of the time. He talks about guides from the astral plane
and from other worlds who helped him. Some pointed him in the
direction of esoteric plant recipes and mind-enhancing drugs (but he
emphasized they only enhanced his powers and were not the source of
them). One apparently bestowed on him a mirror during one of his
meditations. The mirror was especially important to his predictions.
Nostradamus also talked of using different crystals to focus on
various telepathic frequencies. Occasionally he refers to staring at
fire or water (such as in a bowl on a tripod) as a way of focusing
his mind. He had access to some lost works of mysticism from his
travels (apparently to some Moslem lands). He communicated with other
expert astrologers and mystical teachers. However it is possible that
some of his notes about and explanations of his techniques were a
means of throwing the Inquisition off track.
One of the most amazing possibilities explored in various places in
the D.Cannon books was that in a sort of "twist of time" Nostradamus
was tapping into the subconscious of the people from the future who
contacted him. D.Cannon talks about this in the introduction of II.
Some have wondered about Nostradamus' healing capabilities. He talks
about a sort of holistic approach to health and reveals that he was
skillful in avoiding the shock that was induced in many patients of
surgeons at the time using psychic approaches. He talked about the
importance of the "aura" of the person in determining the health of
the patient and criticized the practice of treating symptoms. He said
that a patient will find some other way to make themselves sick if
their critical mental attitude is awry. He talked about cancer being
caused by deeply ingrained self-sabotaging thoughts. Nostradamus also
confirmed what many have speculated, that he was able to see future
approaches to treating the diseases he encountered (such as the
plague) and adopt key aspects of the techniques.