Speaking of Words: Verb Tense and Verb Aspect

Tense can be defined as the point on the time-line that the action expressed by the verb takes place, with reference to the act of speaking, and in English there are three such points: past, present, and future.  Quite a few languages have more than three. 

Speaking of Words: Grammaticalization

This rather alarming word does not refer to what might happen to pupils who go to grammar school but to a simple concept in linguistics that goes a long way toward explaining how languages change over time.