I've used the phrase more than once, but in this answer I wrote:

closing thoughts: Realistic orbits are not perfect conics, and so they and their Keplerian elements do not represent realistic orbits. They are only approximations to reality, and so are not right even though they are close.

 

Keplerian elements were used when people were writing with feathers using light from burning animal fat (if they were not busy being burned at the stake themselves). They are a mixed blessing in the 21st century when everything has so many more digits.

I understand that I am probably jumbling a few different centuries together there, but I am wondering about the hardware more than the politics.

In the fields of mathematics and orbital mechanics, say from Kepler to Lagrange, were mathematical derivations and computations done with pens made from feathers, and if an inspiration came after sundown, was light often as not produced by animal fat, whale oil, or the like?

I've used the phrase more than once, but in this answer I wrote:

closing thoughts: Realistic orbits are not perfect conics, and so they and their Keplerian elements do not represent realistic orbits. They are only approximations to reality, and so are not right even though they are close.

Keplerian elements were used when people were writing with feathers using light from burning animal fat (if they were not busy being burned at the stake themselves). They are a mixed blessing in the 21st century when everything has so many more digits.

I understand that I am probably jumbling a few different centuries together there, but I am wondering about the hardware more than the politics.

In the fields of mathematics and orbital mechanics, say from Kepler to Lagrange, were mathematical derivations and computations done with pens made from feathers, and if an inspiration came after sundown, was light often as not produced by animal fat, whale oil, or the like?