Learn and remember history, that the errors not be repeated, and that the wonders bring new wonders.
The works of classical illustration for science and literature, government informational posters, and children's works are are seriously interesting, though rather challenging for a vector conversion project. Converting watercolor, line-work, wood-block print, and other styles to vector leads to some fairly serious hair tearing on occasion. Maintaining as much of the feel of the original pieces as possible while ensuring that the conversions are print-ready sometimes takes a lot longer than expected. Reading the books and collections these images are from, however, is always a joy. If you need a reading list of utter loveliness, these authors and collections are well worth your time, and as the source materia is no longer under copyright you can often find raw archive versions online quite easily.
-Wetdryvac / Wetdryvac.net