More Aspects

The aspects pu'o and ba'o describe situations in which the event is still not going on, or is no longer going on: if you draw a time-line, they are outside of the line corresponding to the event. But beginnings and endings are pretty conspicuous, as moments go. So we often want to point out that we are not before the beginning of the event, but right at the point when it begins; and not after the end of the event, but right at the point when it ends.

To pinpoint your time at the instant when the event begins, the aspect word you use is co'a. So you can say mi co'a tcidu le cukta at the moment when you start reading a book. When you stop reading the book, the aspect is co'u. When you finish reading, on the other hand, the word to use is mo'u. So Lojban makes a distinction between finishing and stopping (before the event would have finished normally).

For this kind of aspect, English normally just uses verbs: start, finish, stop. Lojban likewise allows you to use distinct selbri to express these notions: cfari, mulno, and sisti. Using aspects just lets you express things more succinctly; and with Lojban the way it is, anything that makes things more succinct comes in handy.

There are more aspects in Lojban, though you won't necessarily see them as often in Lojban text; you can find out about them in Chapter 10.10 of The Complete Lojban Language.