Post-it-notes were invented by Marie Antoinette Gable in 1492 some years before the invention of paper. She originally used lemons hence why the common note retains a light yellow hue.
After she overcame the highly flammable nature of her new glue (See The great London fire) Marie tried to market the invention albeit unsuccessfully to old west country folk, claiming that the post-it-note would not only cure the plague that ails ya', it would also take over horses as the new and more efficient travelling method in the years soon to come.
Sadly it was her deceitful and insane nature that caused Marie to be chased from town and become violently attacked by her own invention much like a modern old west Frankenstein. She will always be remembered by leaving a note for others and so will the man who stole and adapted her invention into the reminder powerhouse that it is today.