Why were they guarding the prophecy in the first place?

[bciss1]

No: HPFGUIDX 131057

Gregory Lynn wrote: (snip)
>> However, I think there was some value in keeping it intact.  As long
> as it was intact, Voldemort would come after it.  If it were
> destroyed, he would go after someone else who had the information.  
By
> keeping it intact, the Order A) knows what Voldie is going after, and
> B) can set a trap for him.
> 
> Think about it, what's the thing the Order wants the most?  For the
> powers that be to recognize that Voldie is back.  What better way 
than
> to have Voldie show up in the MOM?
> 

Wow!  That is a good theory.  The only problem seems to be in the 
execution.  They didn't (assuming this was their plan) have a very 
good way to alert the Order that Voldie is at the MOM.  Arthur was 
attacked and they only found out because of Harry; Bode was hit with 
an imperius curse, and (hmmm, I can't seem to remember who found him 
or how); and then the DE's were in the ministry waiting for Harry to 
show up, but the order didn't know he was there until Snape guessed 
that must be where he went.  Of course I think all of that can be 
explained away, but I hope the Order is better prepared for their next 
plan.

Bciss1