ascribe any deviation of the actual phenomena from this theory to
disturbing causes. At the same time we confess that what we call
disturbing causes are simply those parts of the true circumstances
which we do not know or have neglected, and we endeavour in future to
take account of them. We thus acknowledge that the so-called
disturbance is a mere figment of the mind, not a fact of nature, and
that in natural action there is no disturbance.

But this is not the only way in which the harmony of the material with
the mental operation may be disturbed. The mind of the mathematician
is subject to many disturbing causes, such as fatigue, loss of memory,
and hasty conclusions; and it is found that, from these and other
causes, mathematicians make mistakes.

I am not prepared to deny that, to some mind of a higher order than
ours, each of these errors might be traced to the regular operation of
the laws of actual thinking; in fact we ourselves often do detect, not
only errors of calculation, but the causes of these errors. This,
however, by no means alters our conviction that they are errors, and
that one process of thought is right and another process wrong. I

One of the most profound mathematicians and thinkers of our time, the
late George Boole, when reflecting on the precise and almost
mathematical character of the laws of right thinking as compared with
the exceedingly perplexing though perhaps equally determinate laws of
actual and fallible thinking, was led to another of those points of
view from which Science seems to look out into a region beyond her own
domain.

"We must admit," he says, "that there exist laws" (of thought) "which