*35. Repeat the Subject when the omission would cause ambiguity or obscurity.*—The omission is particularly likely to cause obscurity after a Relative standing as Subject:—
"He professes to be helping the nation, which in reality is suffering from his flattery, and (he? or it?) will not permit anyone else to give it advice."
The Relative should be repeated when it is the Subject of several Verbs. "All the pleasing illusions which made power gentle and obedience liberal, which harmonized the different shades of life, and which, by a bland assimilation, incorporated into politics the sentiments that beautify and soften private society, are to be dissolved by this new conquering empire of light and reason."
*36. Repeat a Preposition after an intervening Conjunction, especially if a Verb and an Object also intervene.*
"He forgets the gratitude that he owes to those that helped all his companions when he was poor and uninfluential, and (to) John Smith in particular." Here, omit to, and the meaning may be "that helped all his companions, and John Smith in particular." The intervention of the verb and object, "helped" and "companions," causes this ambiguity.
*37. When there are several Verbs at some distance from a Conjunction on which they depend, repeat the Conjunction.*[14]
"When we look back upon the havoc that two hundred years have made in the ranks of our national authors—and, above all, (when) we refer their rapid disappearance to the quick succession of new competitors—we cannot help being dismayed at the prospect that lies before the writers of the present day."
Here omit "when," and we at once substitute a parenthetical statement for what is really a subordinate clause.
In reporting a speech or opinion, "that" must be continually repeated, to avoid the danger of confusing what the writer says with what others say.
"We might say that the Cæsars did not persecute the Christians; (that) they only punished men who were charged, rightly or wrongly, with burning Rome, and committing the foulest abominations in secret assemblies; and (that) the refusal to throw frankincense on the altar of Jupiter was not the crime, but only evidence of the crime." But see (6 b).