Before iPhones and Facebook, a lot of people communicated through hand-written letters. You know, back when dinosaurs still roamed the earth.
And back then, not too many people could read and write. But our clever housewives can—and that's important. So, Falstaff writes the "merry wives" a couple of steamy love notes instead of sending them a dirty text-message or posting something racy on their timelines.
Check out what Mistress Page has to say when she finds out that Falstaff has written duplicate letters. (That's right. Falstaff had the nerve to send these two best friends the same letter.)
I warrant he hath a thousand of these letters writ with blank space for different names—sure, more—and these are of the second edition. He will print them, out of doubt; for he cares not what he puts into the press, when he would put us two. I had rather be a giantess and lie under Mount Pelion. (2.1.74-80)
Here, Mistress Page compares Falstaff's writing to the kind of literature that's mass-produced by the printing press (a fairly recent invention when Shakespeare wrote the play). In other words, Mistress Page thinks the love letters are unoriginal and therefore can't possibly be sincere. What's interesting is that she goes on to compare the letters to Falstaff's promiscuous ways. She says that Falstaff doesn't care what he "puts into the [printing] press" just like he doesn't care who he "presses" to his body. In other words, Falstaff's sexual partners are just as interchangeable as the duplicate love letters.
This isn't the first time Shakespeare bags on mass-produced literature in the play. Remember when Slender says he wishes he had his fancy "book of Songs and Sonnets" (1.1.194) to help him romance Anne? That's a reference to a famous book of love poems called Tottel's Miscellany (1557), an anthology that was full of outdated and cheesy clichés.
What's our point? Well, we think Shakespeare the poet is trying to tell us something about his own craft. Here's what his message boils down to: unoriginal and uninspired writing is like casual sex. Guys like Falstaff might think it's fun for a while but, in the end, it's empty and meaningless. And smart ladies know better.