HARTSOEKER, Nicolas

Essay de Dioptrique

Paris: Jean Anisson, 1694

First edition.

small 4to.

Contemporary calf, gilt spine.

Which would be the worse fate for a scientist? To have your work lapse into obscurity and then disappear from the public mind, or to have an unflattering misrepresentation take root and flourish as the only reminder that you ever existed?

Niklaas Hartsoeker (1656 - 1725) was an optical craftsman and observer in the early days of microscopy. He made and used optical instruments for a wide range of original observations, was involved with such luminaries as Huygens and Newton, and enjoyed a noteworthy reputation at least into the mid-eighteenth century. By all rights he should be remembered today as an important pioneer in optics and microbiology. Instead, his place in history has been unjustly reduced to that of a bad example - an illustration of how not to do science. All because of a picture.

Hartsoeker, like Leewenhoek, Malpighi, and others, was a preformationist at a time when explanations of animal reproduction were a confused blend of Aristotelian theory, religious orthodoxy, and pure speculation. He was arguably the first person to observe spermatozoa, using microscopes of his own construction. He collected nearly twenty years of scientific thought and experience into his Essay de Dioptrique (Paris, 1694). Towards the end of that book he presented a picture of a little preformed human figure in the head of a spermatozoon. This picture has since become famous and more than a little notorious as an example of observations biased by theoretical prejudice. Hartsoeker's reputation has been forever linked to this picture and if his name appears today at all, he is usually held up as an example of a scientist who saw what he wanted to see. That was not, in fact, the case. In the text accompanying this famous picture he says:

"si l'on pouvoit voir le petit animal au travers de la peau qui le cache, nous le verrions peut-etre comme cette figure le represente, sinon que la tete seroit peut-etre plus grande a proportion du reste du corps, qu'on ne l'a deffinee ici."

I.e., if one's instruments were good enough, here is a suggestion of what one might see.

Although a preformationist, Hartsoeker never claimed to have actually seen a preformed homunculus. Nevertheless, his popular position in scientific history today is chiefly as an example of a subjective, biased observer doing bad science.

As a postscript, it is useful to note that, to a large extent, the popular misrepresentation of Hartsoeker has been passed along by scientific authors who obviously never consulted his original book. This underscores the importance of using primary sources even when they are difficult to obtain.

from Nicolas Hartsoeker, Essay de dioptrique, Paris 1694.