Happy Birthday in Decemember

I addressed and decorated a handful of Christmas cards this afternoon: because I required Mater's assistance in a related minor matter, I dashed off a few appropriately merry sentiments while the telephone rested between my chin and my shoulder.
As I scribbled, I listened, in part, to Mater's chatter about a significant birthday celebration and what the day had so far brought. At least, I thought I was half listening; I now suspect that the listening percentage was a great deal higher.
"Do you think," I sought Mater's wisdom after a minute or so, "that it's okay to write HAPPY BIRTHDAY on the front of a Christmas greeting card?"
"Not really," said Mater. "Why would you want to do that?"
"I don't know," I said, "but I've done it just the same."
I threw that particular reject to one side and began again with a measure of determination while I quietly lamented the effort, the stickers and the various coloured attachments that had been lost.
I got the greeting right the second time, having first begged Mater for some seconds of silence so that I could concentrate on the words.
"Do you think," I soon asked Mater for another serving of advice, "that it's okay to spell the month as 'Decemember'?"
Mater, much as I expected, did not think so; but she had very decided notions on the subject of attempting too many tasks at one time.
"I'll try this one more time," I said through my teeth, "but if N. doesn't get a card from me this year, please tell her when you meet her that it wasn't for the want of trying."
Mater promised to do just that.
Frequently the best intentions get no further than the front door; one can only hope that the gist of the sentiment, at least, does not go astray.