17.
The foraging mouse, able to carry home three ears at a time from a box full of ears of corn, could not add more than fourteen ears of corn to its store in fourteen journeys, for it had each time to carry along two ears of its own.
18.
If, with equal quantities of butter and lard, a small piece of butter is taken and mixed into all the lard, and if then a piece of this blend of similar size is put back into the butter, there will be in the end exactly as much lard in the butter as there is butter in the lard.
19.
The fallacy of the equation—
4 - 10 = 9 - 15
4 - 10 + 25⁄4 = 9 - 15 + 25⁄4
and the square roots of these—