[KarlInOhio]

If something required that kind of magnification to see, how did Da Vinci even put them there? Could he see what he was writing? What paint brush did he have back then, that could write that small?

The magnifying glass was invented a couple hundred years before Da Vinci's birth. Painting with a single hair or bristle wouldn't have been too shocking either.

[stuartcr]

You mean all that these scientists used for high magnification, was a magnifying glass? Seems odd that no one thought to use one until now?