Shortest Path Between Two Points

The brachistochrone problem was posed by Johann Bernoulli as a challenge to mathematicians of his time. Newton, at the age of 53, when his scientific activities had diminished, and he was responsible for the Royal Mint, received the problem when he returned tired from work and worked on solving it until morning.

 

When Bernoulli saw Newton's solution, which had been sent to him anonymously, he realized from the answer that it was written by Newton. Bernoulli said that in this solution, the lion's claw is hidden.

When Bernoulli received it, he famously declared he recognized the mystery solver “tanquam ex ungue leonem”, which means “as the lion by its claw.”