Canon Flashback!

So, I've started my slow reread of the series. I just finished book one and started on book two, and it got me thinking. What was Lucius Malfoy thinking when he decided to make use of the diary? I mean...really.

Consider this. Dobby comes to 4PD and tells Harry there's a dangerous plan that's been in the works for months. About a month or two before Harry's birthday, Voldemort as Vapermort fails in his attempt to recorporeate. Does Lucius know about this attempt? Does he believe it? And if he does know about it (which I'm assuming he would since word would come through Draco about what happened at the school, as well as to the school board), then...

a. Does he think it would be great to capitalize on the fear generated by the event?

b. Is he so blase about the possible return of the Dark Lord that he thinks nothing of using one of his possessions? I could understand if he really believed the DL was gone. But so soon after evidence that he's still alive?

It's particularly interesting to reread, knowing what that diary really is and knowing Lucius will pay dearly for his actions.

Thoughts?