You Can't Win By Resigning

Ouch!! Tough lesson learned yesterday at the hands of a player one class ahead of me at the club. 

Of course the resignation was entirely premature. But I could not find Qa4. I just didn't see it. My computer evaluates the position as 0.04 in favor of White after Qa4. In other words, perfectly equal and plenty of chess left to be played. 

But I resigned because I could only find losing continuations. I don't know why I was blind to Qa4, but I was.