Johann Bernoulli by Derek Perez 

Johann Bernoulli was born in Basel, Switzerland  in the year 1667. Many members of the Bernoulli family were mathematicians, and Johann's father was a pharmacist.  The Bernoulli family also consisted of wealthy merchants, who were able to achieve a good education. The city of Basel was a prosperous trade hub in  Switzerland. Johann studied medicine, and successfully obtained a doctor's degree in Basel, 1694. While studying he wrote a thesis on muscle contraction. His father wanted Johann to continue the family spice trade, and continue his studies in medicine however Johann and his brother were interested in mathematics.  Between the years 19691 and 1692, Johann wrote two texts on differential and integral calculus. In 1692 he was then hired buy Guillaume-Francois-Antoine, and Guillaume de l'Hopital they agreed to pay Johann for mathematical discoveries. During the years 1695 to 1705, Johann taught mathematics in Groningen, Netherlands. Johann and his brother often worked to solve the same math problems, nevertheless difficulty came when each brother had his own idea or method , and was not supported by the other. Both brothers were interested in the shape of a ship's sail filled with wind.When his older brother, Jakob Bernoulli died of tuberculosis he assumed a professorship position at Basel. Throughout his life , Johann and his brother Jakob  always  had a  competitive relationship.  Johann was always jealous of others, first with his brother Jakob and then his son Daniel. He was jealous of his sons talents that he published a book and changed the date based on his son's works. However, soon his student Guillaume de l'Hopital would take Johann's work and publish it as his own. The book was based on Johann's lectures, and Guillaume took all the credit, even today the problem of zero divided by zero is known as "l'Hopital's rule" and not "Bernoulli's rule". In 1713 Johann defended the mathematician Lebinz, in the Newton-Lebinz debate, he argued that Lebinz should deserve credit for discovering calculus. Johann Bernoulli mainly studied Calculus and produced texts in differential equations. Johann was instrumental in understanding, and making the newly  discovered field of Calculus easy to understand for others. In his later life Johann worked on the principles of mechanics, his works were published in Opera Johannis Bernoullii, four volume in the year 1742.  In the year 1735 his essay started the beginnings of the principle of conservation energy. Johann died on January 1, 1748 in his hometown of Basel. His legacy is carried on by his sons Nicolaus, Daniel, and Johann Jr., they all became mathematicians like their father.