Leeuwenhoek

I remember wondering about Leeuwenhoek's amazing lenses that let him make his not-reproduced-for-a-century observations using the weirdest looking microscope ever. He refused to tell anybody how he made them.

At TU Delft they put one of his microscopes in a neutron tomography system to get a non-destructive look at the details.

It was a simple process, already known--melt a glass rod and led a bead form on the end. Use that bead.

I guess the secret was just patience and quality control. I suppose that's still a useful secret.