wording

effectivescala.mo

@@ -1490,9 +1490,10 @@ other situation.
 Concurrent systems are greatly complicated by the need to coordinate
 access to shared data and resources.
 [Actors](http://www.scala-lang.org/api/current/scala/actors/Actor.html)
-encourage a different approach: each actor is a sequential process
+present one strategy of simplification: each actor is a sequential process
 that maintains its own state and resources, and data is shared by
-messaging with other actors.
+messaging with other actors. Sharing data requires communicating between
+actors.
 
 Offer/Broker builds on this in three important ways. First,
 communication channels (Brokers) are first class -- that is, you send