The term tense would seem to be the least understood term in linguistics It does not and can not indicate the time setting of the verb because it only means something when compared to the time setting the verb relates to There are only two tenses the past and the non past Tense is solely chosen by the speaker Verbs relate to either the past or the non past This is solely determined from the context Perfect verbs relate to the time period that follows the one in which the actions or states occur Imperfect verbs relate to the same time period The time periods past of the past and past occur in the past time zone The present and future time periods occur in the non past time zone If the tense matches the time zone the verb is natural If they do not match then the verb is unnatural Natural verbs can be taken at face value Unnatural verbs require deeper analysis An unnatural verb in the past tense is either hypothetical or is informing the listener that the speaker is less friendly than usual An unnatural verb in the present tense informs the listener that the speaker is more friendly than usual In English teaching there is a structure described as a third conditional All text books describe this as an hypothetical event in the past and all text books are wrong to do so If the actions described by the verbs occur in the past of the past then it is as likely that the condition has been met as it is that the condition in a first conditional e g If it rains we will get wet will be met Only third conditionals whose verbs relate to the non past time zone are hypothetical That traditional grammar descriptions of tense are wrong can be easily seen from a line in a Bob Seger song I wish I did not know now what I did not know then Traditional grammar describes both verbs as being past simple Yet they can not have the same description because they have different meanings They are more correctly descibed as non past simple in the past tense and past simple in the past tense respectively Mel Tisdale