has become probable that a certain class of very bright stars
known as Orion stars--because there are many of them in the most
brilliant of our constellations--which are scattered along the
whole course of the Milky Way, have one and all, in the general
average, slower motions than other stars. Here again we have a
definable characteristic extending through the universe. In
drawing attention to these points of similarity throughout the
whole universe, it must not be supposed that we base our
conclusions directly upon them. The point they bring out is that
the universe is in the nature of an organized system; and it is
upon the fact of its being such a system that we are able, by
other facts, to reach conclusions as to its structure, extent, and
other characteristics.

One of the great problems connected with the universe is that of
its possible extent. How far away are the stars? One of the
unities which we have described leads at once to the conclusion
that the stars must be at very different distances from us;
probably the more distant ones are a thousand times as far as the
nearest; possibly even farther than this. This conclusion may, in
the first place, be based on the fact that the stars seem to be
scattered equally throughout those regions of the universe which
are not connected with the Milky Way. To illustrate the principle,
suppose a farmer to sow a wheat-field of entirely unknown extent
with ten bushels of wheat. We visit the field and wish to have
some idea of its acreage. We may do this if we know how many
grains of wheat there are in the ten bushels. Then we examine a
space two or three feet square in any part of the field and count
the number of grains in that space. If the wheat is equally
scattered over the whole field, we find its extent by the simple