Das entdeckte Geheimnis der Natur im Bau und in der Befruchtung der Blumen

Sprengel's ideas were rejected by other naturalists when it was published,[1] but the importance of this work was duly appreciated by Charles Darwin some sixty years later.

[2] The fact that flowers have a sexual role had been recognised earlier by Linnaeus who did not investigate any functional significance of the visits of insects, but by Sprengel's time it was known that they were sometimes involved in fertilisation.

Sprengel's book introduced a functional view, which would today be called ecology, and provided evidence that pollination was an organised process in which insects acted as "living brushes" in a symbiotic relationship for the teleological purpose of fertilising the flowers.

His discovery enabled him to understand the construction and arrangement of the parts of flowers, but he was puzzled by some features such as the lack of nectar in orchids.

[6] A year later, Darwin wrote to his friend the botanist Joseph Dalton Hooker about the need for insects to pollinate flowering plants; "have you ever seen C. Sprengels curious book on this subject; I have verified many of his observations: doubtless he rides his theory very hard.