Maria Sibylla Merian (1647-1717) was "One of the first and most important entomologist". She "classified many new insect species" and "carefully illustrated the metamorphosis of the butterfly".
I learn a lot from these Rachel Ignotofsky postcards sent by Phillip (the USA).
[Update: I have just learned through Twitter that today Maria Sibylla Merian was born on 2 April. How coincidental!]
More blue butterflies:
Contrasting with the nice cancellation on Phillip's envelope...
Luckily, I got these again!