re than once
without concluding that the coincidence is more than fortuitous.

For example, if we live in a neighbourhood possessed of many black
cats, and sally forth to our daily business in the morning, a
misfortune in the course of the day might more than once follow upon
our meeting a black cat as we went out without raising in our minds
any presumption that the one event was the result of the other.

Certain planets are above the horizon at certain periods of the year
and below the horizon at certain other periods. All through the year
men and women are born who afterwards achieve distinction in various
walks of life, in love, in war, in business, at the bar, in the
pulpit. We perceive a certain number of coincidences between
the ascendancy of certain planets and the birth of distinguished
individuals without suspecting that planetary influence was concerned
in their superiority.

Marriages take place on all days of the year: the sun shines on a good
many days at the ordinary time for such ceremonies; some marriages are
happy, some unhappy; but though in the case of many happy marriages
the sun has shone upon the bride, we regard the coincidence as merely
accidental.

Men often dream of calamities and often suffer calamities in real
life: we should expect the coincidence of a dream of calamity followed
by a reality to occur more than once as a result of chance. There are
thousands of men of different nationalities in business in London,
and many fortunes are made: we should expect more than one man of any
nationality represented there to make a fortune without arguing any
connexion between his nationality and his success.

We allow, then, for a certain amount of repeated coincidence without
presuming causal connexion: can any rule be laid down for determining
the exact amount?

Prof. Bain has formulated the following rule: "Consider the positive
frequency of the phenomena themselves, how great frequency of
coincidence must follow from that, supposing there is neither
connexion nor repugnance. If there be greater frequency, there is
connexion; if less, repugnance."

I do not know that we can go further definite in precept. The number
of casual coincidences bears a certain proportion to the positive
frequency of the coinciding phenomena: that proportion is to be
determined by common-sense in each case. It may be possible, however,
to bring out more clearly the principle on which common-sense proceeds
in de