1. Every paragraph should possess _unity_, that is, it should have a
definite subject or topic to which all parts of the structure are
related, forming elements, in its development.
2. The sentences that compose a paragraph should follow one another in
natural order, showing a logical progress of thought. This principle is
called _continuity_.
3. The connection of each sentence in the paragraph, with the preceding
one, should be made clear, and also the connection between the
paragraphs themselves.
This connection or explicit reference is secured in the following
ways:—
1. By conjunctions and adverbs.
2. By demonstrative words and phrases.
3. By a clear and unmistakable _connection in sense_.