I did this drawing in 1979, at which time a best selling novel, "Fear of Flying" by Erica Jong, had as its theme human female laciviousness (towards the human male). In this novel the woman protagonist finally fulfills her fantasy of a casual affair, but in the end returns to her rather boring husband.
 
Now there has always been a certain amount of joking and more or less deliberate mis-understanding by men about the tendency of girls and women to be "horse crazy", and in many cases there is probably involved some jealousy by the man towards the horse.
 
So this drawing is the cover illustration for my proposed erotic equestrian novel, a "Fear of Flying Changes, a dirty dressage novel." . (Flying changes is an equestrian term for the horse switching which leg "leads" at a canter or gallop. To do flying changes at every stride is one of the more difficult requirements of the Grand Prix dressage test at the Olympics. The horse in the drawing is actually doing the piaffe, which is another of the most difficult movements of Grand Prix dressage. ) I don't recall ever having gotten as far as constructing a plot for the novel, but it probably would have had the woman protagonist having an affair with a man, but in the end going back to her horse, who is of course much more beautiful, a much more exciting ride, and completely obediant to her every slightest request. The limerick below is all that I ever wrote for this novel.