An introduction to mathematics, by A. N. Whitehead.

26 INTRODUCTION TO MATHEMATICS
particular man. They are stated in an abstract general way, with complete indifference to the owner's state of mind when he
has to pay the bill.
Now think a bit further as to what all this
means. The building of a house is a complicated set of circumstances. It is impossible to begin to apply the law, or to test
it, unless amid the general course of events
it is possible to recognize a definite set of
occurrences as forming a particular instance
of the building of a house. In short, we must
know a house when we see it, and must
recognize the events which belong to its
building. Then amidst these events, thus
isolated in idea from the rest of nature, the
two elements of the cost and cubic content
must be determinable; and when they are
both determined, if the law be true, they
satisfy the general formula
20y =x.
But is the law true? Anyone who has had
much to do with building will know that we
have here put the cost rather high. It is
only for an expensive type of house that it
will work out at this price. This brings out
another point which must be made clear.
While we are making mathematical calculations connected with the formula 20y =x, it
is indifferent to us whether the law be true or