With time, the speaker indicates the moment at which the content of his communication takes place in his representation. In New Testament Greek, there are only three tenses: during, before and after the moment of speech. These three are called present, past and future tenses. The words italicized in the following example are translations of Greek verb forms indicating a past, a present and a future tense, respectively (see Matt. 5:2 and 6:21):

And He taught them: where your treasure is, there your heart will be also.

See further at grammar.