Mark Twain Did Not Write Valentines

Mark Twain is deservedly remembered for his barbed wit, for lines like these from his Notebooks:

"Familiarity breeds contempt -- and children."

"There has been only one Christian. They caught him and crucified him -- early."

But every now and then he's picked as the avatar of inspiration or even what Oscar Wilde called "more than usually revolting sentimentality."

Exhibit A, found all over the Internet, including that inexhaustible source of misquotations Goodreads:





Could anyone...