The difference is that the empiricists are less dazzled.  Unity doesn’t blind them to everything else, doesn’t quench their curiosity for special facts, whereas there is a kind of rationalist who is sure to interpret abstract unity mystically and to forget everything else, to treat it as a principle; to admire and worship it; and thereupon to come to a full stop intellectually.

’The world is One!’—­the formula may become a sort of number-worship.  ‘Three’ and ‘seven’ have, it is true, been reckoned sacred numbers; but, abstractly taken, why is ‘one’ more excellent than ‘forty-three,’ or than ‘two million and ten’?  In this first vague conviction of the world’s unity, there is so little to take hold of that we hardly know what we mean by it.

The only way to get forward with our notion is to treat it pragmatically.  Granting the oneness to exist, what facts will be different in consequence?  What will the unity be known-as?  The world is one—­yes, but how one?  What is the practical value of the oneness for us?

Asking such questions, we pass from the vague to the definite, from the abstract to the concrete.  Many distinct ways in which oneness predicated of the universe might make a difference, come to view.  I will note successively the more obvious of these ways.

1.  First, the world is at least one subject of discourse.  If its manyness were so irremediable as to permit no union whatever of it parts, not even our minds could ‘mean’ the whole of it at once:  the would be like eyes trying to look in opposite directions.  But in point of fact we mean to cover the whole of it by our abstract term ‘world’ or ‘universe,’ which expressly intends that no part shall be left out.  Such unity of discourse carries obviously no farther monistic specifications.  A ‘chaos,’ once so named, has as much unity of discourse as a cosmos.  It is an odd fact that many monists consider a great victory scored for their side when pluralists say ‘the universe is many.’ “’The universe’!” they chuckle—­“his speech bewrayeth him.  He stands confessed of monism out of his own mouth.”  Well, let things be one in that sense!  You can then fling such a word as universe at the whole collection of them, but what matters it?  It still remains to be ascertained whether they are one in any other sense that is more valuable.

2.  Are they, for example, continuous?  Can you pass from one to another, keeping always in your one universe without any danger of falling out?  In other words, do the parts of our universe hang together, instead of being like detached grains of sand?

Even grains of sand hang together through the space in which they are embedded, and if you can in any way move through such space, you can pass continuously from number one of them to number two.  Space and time are thus vehicles of continuity, by which the world’s parts hang together.  The practical difference to us, resultant from these forms of union, is immense.  Our whole motor life is based upon them.