The PRESENT TENSE represents an action or event as taking place at the time in which it is mentioned; as, “I smile; I see; I am seen.”

    NOTE 1.  The present tense is also used in speaking of actions
    continued, with occasional intermissions, to the present time; as,
    “He rides out every morning.”

    2.  This tense is sometimes applied to represent the actions of
    persons long since dead; as, “Seneca reasons and moralizes well;
    An honest man is the noblest work of God.”

3.  When the present tense is preceded by the words, when, before, after, as soon as, &c. it is sometimes used to point out the relative time of a future action; as, “When he arrives we shall hear the news.”

The IMPERFECT TENSE denotes a past action or event, however distant; or,

The IMPERFECT TENSE represents an action or event as past and finished, but without defining the precise time of its completion; as, “I loved her for her modesty and virtue; They were travelling post when he met them.”

In these examples, the verbs loved and met express past and finished actions, and therefore constitute a perfect tense as strictly as any form of the verb in our language; but, as they do not define the precise time of the completion of these actions, their tense may properly be denominated an indefinite past.  By defining the present participle in conjunction with the verb, we have an imperfect tense in the expression, were travelling.  This course, however, would not be in accordance with the ordinary method of treating the participle.  Hence it follows, that the terms imperfect and perfect, as applied to this and the next succeeding tense, are not altogether significant of their true character; but if you learn to apply these tenses correctly, the propriety or impropriety of their names is not a consideration of very great moment.

The PERFECT TENSE denotes past time, and also conveys an allusion to the present; as, “I have finished my letter.”

The verb have finished, in this example, signifies that the action, though past, was perfectly finished at a point of time immediately preceding, or in the course of a period which comes to the present.  Under this view of the subject, the term perfect may be properly applied to this tense, for it specifies, not only the completion of the action, but, also, alludes to the particular period of its accomplishment.

The PLUPERFECT TENSE represents a past action or event that transpired before some other past time specified; as, “I had finished my letter before my brother arrived.”

You observe that the verb had finished, in this example, represents one past action, and the arrival of my brother, another past action; therefore had finished is in the pluperfect tense, because the action took place prior to the taking place of the other past action specified in the same sentence.