Siddhartha Mukherjee in Literary Hub:
Modern genetics was launched by the practice of agriculture: the Moravian monk Gregor Mendel discovered genes by cross-pollinating peas with a paintbrush in his monastery garden in Brno. The Russian geneticist Nikolai Vavilov was inspired by crop selection. Even the English naturalist Charles Darwin had noted the extreme changes in animal forms created by selective breeding. Cell biology, too, was instigated by an unassuming, practical technology. Highbrow science was born from lowbrow tinkering.
In the case of cell biology, it was simply the art of seeing: the world measured, observed, and dissected by the eye. In the early seventeenth century, a Dutch father and son team of opticians, Hans and Zacharias Janssen, placed two magnifying lenses on the top and bottom of a tube and found that they could magnify an unseen world.