When setting up a new iOS device or installing the Messages Beta on OS X, you can log in with your iMessage account to start receiving & sending messages with iMessage.
One advantage of iMessage is that these messages are received on all your devices — meaning that as long as you have iMessage configured on a device, you can see the history of a conversation.
But as far as I can tell, you can only see messages which have been delivered after you set up your iMessage account on a device. Is there a way to load old messages which were sent/received before setting up iMessage? (I'd like to load both old messages within a current conversation/thread, and old conversations which have not recently received messages.)