Page "Imperfective aspect" Paragraph 9

' Was reading ', however, is different.

Besides being the background to ' entered ', the form ' reading ' presents " an internal portion of John's reading, no explicit reference to the beginning or to the end of his reading.

" This is the essence of the imperfective aspect.

Or, to continue the quotation, " the perfective looks at the situation from the outside, without necessarily distinguishing any of the internal structure of the situation, whereas the imperfective looks at the situation from inside, and as such is crucially concerned with the internal structure of the situation, since it can both look backwards towards the start of the situation, and look forwards to the end of the situation, and indeed it is equally appropriate if the situation is one that lasts through all time, without any beginning and without any end.