Tahafut_al-Tahafut-transl-Engl-van-den-Bergh

and is found in Thomas Aquinas and most of the writers about the occult
in the Renaissance, for instance Heinricus Cornelius Agrippa, Paracelsus,
and Cardanus. It may be mentioned here that Avicenna gives as an
example of the power of suggestion that a man will go calmly over a .plank
when it is on the ground, whereas he will hesitate if the plank be across an
abyss. This famous example is found in Pascal’s Pensées, and the wellknown
modern healer, Coué, takes it as his chief proof for the power of
suggestion. Pascal has taken it from Montaigne, Montaigne has borrowed
it from his contemporary the great doctor Pietro Bairo, who himself has a
lengthy quotation from the Psychology of Avicenna. Robert Burton in his
Anatomy of Melancholy also mentions it. In the Middle Ages this example
is found in Thomas Aquinas. Now the philosophers limit the possibility of
miracles only to those that can be explained by the power of the mind over
physical objects; for instance, they would regard it as possible that a
prophet might cause rain to fall or an earthquake to take place, but they
refuse to accept the more extravagant miracles I have mentioned as
authentic.
The theologians, however, base their theory of miracles on a denial of
natural law. The Megarian-Ash‘arite denial of potentiality already implies
the denial of natural law. According to this conception there is neither
necessity nor possibility in rerum natura, they are or they are not, there is
no nexus between the phenomena. But the Greek Sceptics also deny the
rational relation between cause and effect, and it is this Greek Sceptical
theory which the Ash‘arites have copied, as we can see by their examples.
The theory that there is no necessary relation between cause and effect is
found, for instance, in Galen. Fire burns but there is, according to the
Greek Sceptics, no necessary relation between fire and burning. Through
seeing this happen many times we assume that it will happen also in the
future, but there is no necessity, no absolute certainty. This Sceptical
theory is quasi-identical with the theory of Hume and is based on the
same assumptions, that all knowledge is given through sense-impression;
and since the idea of causation cannot be derived from sense experience
it is denied altogether. According to the theory of the theologians, God
who creates and re-creates the universe continually follows a certain habit
in His creation. But He can do anything He desires, everything is possible
for Him except the logically impossible; therefore all logically possible
miracles are allowed. One might say that, for the theologians, all nature is
25