Jean Le Rond d’Alembert was bornon 16 November 1717 in Paris, French, is Mathematician, Physicist, Philosopher And Musical Intellectual. A great mathematician, philosopher and music theoretician, Jean Le Rond d’Alembert was among the most influential men of his time. His “Traité de dynamique”, in which he expounded his own laws of motion, is one of his notable works. He did some outstanding developments in the field of mathematics, particularly, in the ‘foundations of mathematics’. The “d’Alembert theorem” and the “ratio tests” (a test to check if a “series” unites) developed by him is followed in mathematics even now. He expressed a fair amount of interest in physics as well, and thus, came up with the “d’Alembert operator”, which is vital in modern theoretical physics. As a mathematician and physicist, he received reasonable reputation and was therefore chosen to edit articles on mathematics and physics for the French encyclopedia. Later he turned to philosophy, literature and music. Some his philosophical works were highly praised in the salons he attended. Read on to know more about this genius.