The tulips are Zomerschoon (Beauty of Summer), Mabel and Elegans Alba. The illustration is also Zomerschoon - this is a reproduction of a page from the P. Cos Tulip Book of 1637, at the height of Tulipomania, when one single Zomerschoon bulb sold for more than a thousand guilders. It was often painted by the Dutch masters. Most of the paintings in the Cos book were made by Jacob Isaacsz. van Swanenburgh, Rembrandt's first teacher.