Christmas in July

My husband and I were watching Christmas movies on the Hallmark channel and I was wondering where did the saying 'Christmas in July' come from?  Christmas, the commercial part is so stressful, why would we want to do this twice?  For organized people, you are starting your shopping now. Quilters, and crafters are beginning to make their presents and I am designing another quilt for Quilt Market.  Here's a hint.....Log Cabin.  Check back to see what's new.