roofs--horizontal planes--follow, until some portion of
three-dimensional space has been enclosed.

Substantially the same sequence holds, whatever the kind of building
or the character of the construction--whether a steel-framed
skyscraper or a wooden shanty. A line system, represented by columns
and girders in the one case, and by studs and rafters in the other,
becomes, by overlay or interposition, a system of planes, so
assembled and correlated as to define a solid.

With nearly everything of man's creating--be it a bureau or a
battleship--the process is as above described. First, a pattern to
scale; next, an actual linear framework; then planes defining a solid.
Consider almost any of the industries practiced throughout the ages:
they may be conceived of thus in terms of dimensions; for example,
those ancient ones of weaving and basket making. _Lines_ (threads in
the one case, rushes in the other) are wrought into _planes_ to
clothe a body or to contain a burden. Or think, if you choose, of
the modern industry of book-making, wherein types are assembled,
impressed upon sheets of paper, and these bound into volumes--
_points, lines, planes, solids_. The book in turn becomes the unit
of another dimensional order, in the library whose serried shelves
form lines, which, combined into planes, define the lateral limits
of the room.


HIGHER--AND HIGHEST--SPACE

These are truisms. What have they to do, it may be asked, with the
idea of _higher_ spaces? They have everything to do with it, for in