The Droste chocolate factory is going out of business after 161 years! I’m hoping they can restart at a smaller scale because how else will we illustrate recursion?

In a right angle triangle the square on the hypotenuse is equal to the sum...
From "The First Six Books of the Elements of Euclid" written & illustrated by Oliver Byrne, London: 1847

In a given circle to inscribe a square.
From "The First Six Books of the Elements of Euclid" written & illustrated by Oliver Byrne, London: 1847

If a straight line be bisected and produced to any point...
From "The First Six Books of the Elements of Euclid" written & illustrated by Oliver Byrne, London: 1847