nce," "permanence," and "space" are non-existent ideas, _i.e.,_
they are not images in sense. They might, however, be "notions" like
that of "spirit," which Berkeley ingenuously admitted into his system,
to be, mysteriously enough, _that which has_ ideas. Or they might be
(what would do just as well for our purpose) that which he elsewhere
called them, algebraic signs used to facilitate the operations of
thought. This is, indeed, what they are, if we take the word algebraic
in a loose enough sense. They are like algebraic signs in being, in
respect of their object or signification, not concrete images but terms
in a mental process, elements in a method of inference. Why, then,
denounce them? They could be used with all confidence to lead us back
to the concrete values for which they stood and to the relations which
they enabled us to state and discover. Experience would thus be
furnished with an intelligible structure and articulation, and a
psychological analysis would be made of knowledge into its sensuous
material and its ideal objects. What, then, was Berkeley's objection to
these algebraic methods of inference and to the notions of space,
matter, independent existence, and efficient causality which these
methods involve?

[Sidenote: Horror of physics.]

What he abhorred was the belief that such methods of interpreting
experience were ultimate and truly valid, and that by thinking after the
fashion of "mathematical atheists" we could understand experience as
well as it can be understood. If the flux of ideas had no other key to
it than that system of associations and algebraic substitutions which is
called the natural world we should indeed know just as well what to
expect in practice and should receive the same education in perception
and reflection; but what difference would there be between such an
idealist and the most pestilential materialist, save his even greater
wariness and scepticism? Berkeley at this time--long before days of
"Siris" and tar-water--was too ignorant and hasty to understand how
inane all spiritual or poetic ideals would be did they not express man's
tragic dependence on nature and his congruous development in her bosom.
He lived in an age when the study and dominion of external things no
longer served directly spiritual uses. The middle-men had appeared,
those spirits in whom the pursuit of the true and the practical never
leads to possession of the good, but loses itself, like a river in