On the other hand, sentences should contain the whole of one thought;
none of it should run over into another sentence. Strange as it may
seem, sentences are sometimes found like the following: "James was on
the whole a bad boy. But he had some redeeming qualities." "The first
day at school was all new to me. While it was interesting as well."
"He said that he was going. And that I might go with him." There is no
ground for an explanation of such errors as these except laziness and
grossest illiteracy. It is by no device so simple as the insertion of
a period that man can separate what has been joined in thought. _And_
and _but_ rarely begin sentences; in nearly all cases it will be found
that the sentences they purport to connect are but the independent
clauses of one compound sentence. _While_ or any other subordinating
conjunction introduces a dependent clause; a dependent clause is not a
sentence; it can never stand alone.

The offenses against the unity of a sentence are including too much
and including too little. Both are the result of carelessness or
inability to think. The purpose, the kernel, the germ of the sentence,
should be so clearly in mind that every necessary modification of the
thought shall be included and every unnecessary phrase be excluded.
Some further suggestions concerning unity are found in the paragraphs
treating primarily of mass and coherence.

Mass.

As advance is made in the ability to grasp quickly the thought of a
book, it becomes more and more evident that the eye must be taken into
account when arranging the parts of a composition. The eye sees the
headings of the chapters; it catches the last words of one paragraph
and the first words of the next; it lights upon the words near the
periods; so the parts of a composition should be arranged so that
these points shall contain worthy words. Moreover, within the sentence
the colon marks the greatest independence of the parts; the semicolon
comes next; and the comma marks the smallest division of thought.
Following the guidance of the eye, then, the words before a period
should be the most important; those near a colon, a semicolon, and a
comma will have a descending scale of value. A speaker has no
difficulty with punctuation; unconsciously he pauses with the thought.
So true is this, that one is inclined to say that if the writer will
read aloud his own composition, and punctuate where he pauses in the
reading, always remembering t