the conclusion that someone has broken open the window, and stolen
the plate, arrives at that hypothesis--for it is nothing more--by a
long and complex train of inductions and deductions of just the same
kind as those which, according to the Baconian philosophy, are to be
used for investigating the deepest secrets of Nature.

This is true, even of those sciences which involve long mathematical
calculations. In fact, the stating of the problem to be solved is
the most important element in the calculation; and that is so
thoroughly a labour of common sense that an utterly uneducated mart
may, and often does, state an abstruse problem clearly and
correctly; seeing what ought to be proved, and perhaps how to prove
it, though he may be unable to work the problem out for want of
mathematical knowledge.

But that mathematical knowledge is not--as all Cambridge men are
surely aware--the result of any special gift. It is merely the
development of those conceptions of form and number which every
human being possesses; and any person of average intellect can make
himself a fair mathematician if he will only pay continuous
attention; in plain English, think enough about the subject.

There are sciences, again, which do not involve mathematical
calculation; for instance, botany, zoology, geology, which are just
now passing from their old stage of classificatory sciences into the
rank of organic ones. These are, without doubt, altogether within
the scope of the merest common sense. Any man or woman of average
intellect, if they will but observe and think for themselves,
freely, boldly, patiently, accurately, may judge for themselves of
the conclusions of these sciences, may add to these conclusions