The Master of the Brussels Initials is the notname of an artist who decorated gorgeous illuminated manuscripts for royalty like Charles the Noble and the Duke of Berry - perhaps the most extravagant book collector ever to have lived.
This artist, active at the turn of the 14th to 15th century, is notable not only for making works of great beauty, and having an important role in the development of late Gothic art, but also for being a keen observer of nature. The small bug in this full-size miniature depicting the Annunciation, is perfectly identifiable as a firebug, Pyrrhocoris apterus. In fact, G. Evelyn Hutchinson, the "father of modern ecology", wrote an entire fascinating article about the Master of the Brussels Initials and insects depicted by him, available here. He argued that this was more than a curiosity, it was an example of a development within manuscript decoration towards a more naturalistic world view, "part of the same movement that produced the contemporary studies of optics and mechanics in England, France and Germany" and which continued with the production of formal natural history treaties in the 16th century.
So, while it may not have been the only such seed, one impulse to the modest beginning which would eventually give us modern science could be said to be found in the beautiful decorations of medieval manuscripts.