MODE, TENSE, NUMBER, AND PERSON.
+Introductory Hints.+—James walks. Here the walking is asserted as an actual fact. James may walk. Here the walking is asserted not as an actual, but as a possible, fact. If James walk out, he will improve. Here the walking is asserted only as thought of, without regard to its being or becoming either an actual or a possible fact. James, walk out. Here the walking is not asserted as a fact, but as a command—James is ordered to make it a fact. These different uses and forms of the verb constitute the modification which we call +Mode.+ The first verb is in the +Indicative Mode;+ the second in the +Potential Mode;+ the third in the +Subjunctive Mode;+ the fourth in the +Imperative Mode.+
For the two forms of the verb called the +Participle+ and the +Infinitive,+ see Lessons 37 and 40.
I walk. I walked. I shall walk. In these three sentences the manner of asserting the action is the same, but the time in which the action takes place is different. Walk asserts the action as going on in present time, and, as +Tense+ means time, is in the +Present Tense.+ Walked asserts the action as past, and is in the +Past Tense.+ Shall walk asserts the action as future, and is in the +Future Tense.+
I have walked out to-day. I had walked out when he called. I shall have walked out by to-morrow. Have walked asserts the action as completed at the present, and is in the +Present Perfect Tense.+ Had walked asserts the action as completed in the past, and is in the +Past Perfect Tense.+ Shall have walked asserts action to be completed in the future, and is in the +Future Perfect Tense.+
I walk. Thou walkest. He walks. They walk. In the second sentence walk is changed by adding +est+; in the third sentence, by adding +s.+ Verbs are said to agree in +Person+ and +Number+ with their subjects. But this agreement is not generally marked by a change in the form of the verb.
+DEFINITIONS+.
+Mode is that modification of the verb which denotes the manner of asserting the action or being+.
+The Indicative Mode asserts the action or being as a fact+. [Footnote: In "Are you going?" or "You are going?" a fact is referred to the hearer for his admission or denial. In "Who did it?" the fact that some person did it is asserted, and the hearer is requested to name the person. It will be seen that the Indicative Mode may be used in asking a question.]
+The Potential Mode asserts the power, liberty, possibility, or necessity of acting or being+.