There are four simple moods,—the Infinitive, the Indicative, the Imperative and the Subjunctive.
The Mood of a verb denotes the mode or manner in which it is used. Thus if it is used in its widest sense without reference to person or number, time or place, it is in the Infinitive Mood; as "To run." Here we are not told who does the running, when it is done, where it is done or anything about it.
When a verb is used to indicate or declare or ask a simple question or make any direct statement, it is in the Indicative Mood. "The boy loves his book." Here a direct statement is made concerning the boy. "Have you a pin?" Here a simple question is asked which calls for an answer.
When the verb is used to express a command or entreaty it is in the Imperative Mood as, "Go away." "Give me a penny."
When the verb is used to express doubt, supposition or uncertainty or when some future action depends upon a contingency, it is in the subjunctive mood; as, "If I come, he shall remain."
Many grammarians include a fifth mood called the potential to express power, possibility, liberty, necessity, will or duty. It is formed by means of the auxiliaries may, can, ought and must, but in all cases it can be resolved into the indicative or subjunctive. Thus, in "I may write if I choose," "may write" is by some classified as in the potential mood, but in reality the phrase I may write is an indicative one while the second clause, if I choose, is the expression of a condition upon which, not my liberty to write, depends, but my actual writing.
Verbs have two participles, the present or imperfect, sometimes called the active ending in ing and the past or perfect, often called the passive, ending in ed or d.
The infinitive expresses the sense of the verb in a substantive form, the participles in an adjective form; as "To rise early is healthful." "An early rising man." "The newly risen sun."
The participle in ing is frequently used as a substantive and consequently is equivalent to an infinitive; thus, "To rise early is healthful" and "Rising early is healthful" are the same.
The principal parts of a verb are the Present Indicative, Past Indicative and Past Participle; as:
|Present ||Past ||Passive Participle|
|Can ||Could ||(Wanting)|
|May ||Might ||"|
|Shall ||Should ||"|
|Will ||Would ||"|
|Ought ||Ought ||"|
Verbs may also be divided into principal and auxiliary. A principal verb is that without which a sentence or clause can contain no assertion or affirmation. An auxiliary is a verb joined to the root or participles of a principal verb to express time and manner with greater precision than can be done by the tenses and moods in their simple form. Thus, the sentence, "I am writing an exercise; when I shall have finished it I shall read it to the class." has no meaning without the principal verbs writing, finished read; but the meaning is rendered more definite, especially with regard to time, by the auxiliary verbs am, have, shall.
There are nine auxiliary or helping verbs, viz., Be, have, do, shall, will, may, can, ought, and must. They are called helping verbs, because it is by their aid the compound tenses are formed.