The artist is Sergei Dmitrievich Merkurov. He would go on to become an honored sculptor and state artist. The reason for an erotic alphabet? Supposedly for the elimination of illiteracy among the adult population in the countryside. But probably, because it was fun. Way heavy on the ancient Roman influence: horny satyrs, indecent cupids, and flying disembodied cocks. They don’t tell you this, but for some reason the ancient Romans drew about a million pictures of cocks with wings. The ancient Romans appreciated few of the nuances of modern workplace behavior.
Did I MENTION not safe for work?