“This was to me, among all the marvels that I have discovered in Nature, the most marvellous of all; and I must say for my part, that no greater pleasure has yet come to my eye than these spectacles of so many thousands of living creatures in a small drop of water moving among one another, each individual creature with its particular movement.

My method for seeing the very smallest animalcules I do not impart to others; nor how to see very many animalcules at one time. This I keep for myself alone.”

Anton van Leeuwenhoek, 1676.