a
few pellucid sentences, such fullness and amplitude of treatment will be
only a hindrance, and will give the reader nothing but indefinite
notions. Therefore, when I mention obscure terms, and the symmetrical
proportions of members of buildings, I shall give brief explanations, so
that they may be committed to memory; for thus expressed, the mind will
be enabled to understand them the more easily.

3. Furthermore, since I have observed that our citizens are distracted
with public affairs and private business, I have thought it best to
write briefly, so that my readers, whose intervals of leisure are small,
may be able to comprehend in a short time.

Then again, Pythagoras and those who came after him in his school
thought it proper to employ the principles of the cube in composing
books on their doctrines, and, having determined that the cube consisted
of 216[6] lines, held that there should be no more than three cubes in
any one treatise.

[Note 6: Codd. _CC. & L._]

4. A cube is a body with sides all of equal breadth and their surfaces
perfectly square. When thrown down, it stands firm and steady so long as
it is untouched, no matter on which of its sides it has fallen, like the
dice which players throw on the board. The Pythagoreans appear to have
drawn their analogy from the cube, because the number of lines mentioned
will be fixed firmly and steadily in the memory when they have once
settled down, like a cube, upon a man's understanding. The Greek comic
poets, also, divided their plays into parts by introducing a choral
song, and by this partition on the principle of the cubes, they relieve
the actor's speeches by such intermissions.

5. Since these rules, founded on the analogy of nature, were followed by
our predecessors, and since I observe that I have to write on unusual
subjects which many persons will find obscure, I have thought it best to
write in short books, so that they may the more readily strike the
understanding of the reader: for they will thus be easy to comprehend. I
have also arranged them so that those in search of knowledge on a
subject may not have to gather it from different places, but may find it
in one complete treatment, with the various classes set forth each in a
book by itself. Hence, Caesar, in the third and fourth books I gave the
rules for temples; in this book I shall treat of the laying out of
public places. I shall speak first of the proper arrangement of the
forum, for in