One day many years ago, when Leonardo da Vinci was in Rome, the Pope sent an emissary to see Leonardo requesting (although in those days a request was an order) that he submit some of his works to be in competition for a new commission.
Leonardo replied, that he was too busy and could not submit any works at that time.
The Pope sent the emissary a second time, requesting that Leonardo submit some of his work. Again Leonardo refused, stating that he was still too busy.
When the emissary arrived the third time, he had a message from the Pope for Leonardo. This being that, if Leonardo did not submit some of his work now, the Pope would have him thrown in prison.
In response to this, Leonardo made a statement similar to that being, "if the Pope really has to have some of my work submitted, then here; take this to the Pope." Where upon he immediately at arms length, took his paintbrush, and drew a circle, in a complete free hand style, and without a support of any kind, and gave it to the emissary to take to the Pope.
What he had actually done, was to have drawn a perfect circle, when measured by a protractor, at arms length, in a complete free hand style, and without a support of any kind. He naturally received the commission.