theless, a "scientific truth" in the present
condition of our knowledge.

This final but unknown "truth valid in infinity" is somehow perceived or
felt by us as an ideal, for in countless years of observation we have
formed a series of less and less false, more and more nearly true "ideas"
about the phenomenon. The "ideas" are _reflexes_ of the phenomenon,
reflected in our midst as in a mirror; the reflexes may be distorted, as
in a convex or concave mirror, but they suggest an ideal reflex valid in
infinity. It is of the utmost importance to realize that the words which
are used to express the ideas and the ideals are THE MATERIALIZATION of
the ideas and ideal; it is only by words that we are enabled to give to
other human beings an exact or nearly exact impression which we have had
of the phenomenon.

It may be helpful to illustrate this process by an example. Let us suppose
that a man makes an experiment of doing his own portrait from a mirror,
which may be plane, concave or convex. If he looks into a plane mirror, he
will see his true likeness; even so, if he be a poor designer, he will
draw the likeness badly. Let us suppose that the man has beautiful
features but because the drawing is very poor, it will not convey the
impression that the features of the original were beautiful. If this poor
designer were to look into and work from a concave or convex mirror, the
drawing of his likeness would have practically no resemblance to his
original features.

For correct analysis and true definitions of the cardinal classes of life
in our world it is necessary to have some just ideas about dimensions or
dimensionality. The Britannica gives us some help in this connection. I
will explain briefly by an example. Measurable entities of different kinds
can not be compared directly. Each one must be measured in terms of a unit
of its own kind. A line can have only length and therefore is of one
dimension: a surface has length and width and is therefore said to have
two dimensions; a volume has length, width and thickness and is,
therefore, said to have three dimensions. If we take, for example, a
volume--say a cube--we see that the cube has surfaces and lines and points,
but a volume is not a surface nor a line nor a point. Just these
dimensional differences have an enormous unrealized importance in
practical life, as in the case of taking a line of five units of length
and building upon it a square, the measure of this square