306. Shall and should are often used in the second and third persons in subordinate clauses to express volition which is not that of the subject.

307. When a clause with that states something, not as a fact but as an idea to be considered, should is the proper auxiliary in all three persons.

308. For shall and will, should and would, in indirect discourse, see [§§ 438–439].

THE INFINITIVE

309. The infinitive is a verb-form that has some of the properties of a noun ([§ 28]). Its two-sided character comes out clearly when it is used as the subject of a sentence.

Each of these infinitives (to hope, to flatter, etc.) is a noun, for each is the simple subject of a sentence. Besides, an ordinary noun may be substituted for each infinitive with no change in meaning; as,—“Hope is our only resource”; “Flattery is not my custom”; “Sleep was an impossibility.”