he star, in the sense in which a man is part of the human race.

But presently the light of the star reaches our atmosphere. It begins
to be refracted, and dimmed by mist, and its velocity is slightly
diminished. At last it reaches a human eye, where a complicated process
takes place, ending in a sensation which gives us our grounds for
believing in all that has gone before. Now, the irregular appearances of
the star are not, strictly speaking, members of the system which is the
star, according to our definition of matter. The irregular appearances,
however, are not merely irregular: they proceed according to laws which
can be stated in terms of the matter through which the light has
passed on its way. The sources of an irregular appearance are therefore
twofold:

(1) The object which is appearing irregularly;

2) The intervening medium.

It should be observed that, while the conception of a regular appearance
is perfectly precise, the conception of an irregular appearance is one
capable of any degree of vagueness. When the distorting influence of the
medium is sufficiently great, the resulting particular can no longer be
regarded as an appearance of an object, but must be treated on its own
account. This happens especially when the particular in question cannot
be traced back to one object, but is a blend of two or more. This case
is normal in perception: we see as one what the microscope or telescope
reveals to be many different objects. The notion of perception is
therefore not a precise one: we perceive things more or less, but always
with a very considerable amount of vagueness and confusion.

In considering irregular appearances, there are certain very natural
mistakes which must be avoided. In order that a particular may count as
an irregular appearance of a certain object, it is not necessary that
it should bear any resemblance to the regular appearances as regard
its intrinsic qualities. All that is necessary is that it should be
derivable from the regular appearances by the laws which express
the distorting influence of the medium. When it is so derivable,
the particular in question may be regarded as caused by the regular
appearances, and therefore by the object itself, together with the
modifications resulting from the medium. In other cases, the particular
in question may, in the same sense, be regarded as caused by several
objects together with the medium; in this case, it may be called a
confused app