The lemniscate of Bernoulli was discovered by Jakob Bernoulli in 1694 as the modification of the ellipse. The lemniscate is the locus whose product of the distances from one point $\text{P}$ to each of the two foci $\text{F}_1$ and $\text{F}_2$ is constant.

You can interact with it below. Click in the play button in the bottom left corner to begin the animation that shows the drawing of a lemniscate. To see the circles involved in the curve drawing, click Show the circles.