From Wikipedia

Joy of mathematics

Part Two

Through the use of abstraction and logical reasoning, mathematics evolved from counting, calculation, measurement, and the systematic study of the shapes and motions of physical objects. Practical mathematics has been a human activity for as far back as written records exist. Rigorous arguments first appeared in Greek mathematics, most notably in Euclid's *Elements*. Mathematics continued to develop, for example in China in 300 BC, in India in AD 100, and in the Muslim world in AD 800, until the Renaissance, when mathematical innovations interacting with new scientific discoveries led to a rapid increase in the rate of mathematical discovery that continues to the present day.^{}

Lecture Nine - The Joy of Nine

Lecture Ten - The Joy of Proofs

Lecture Eleven - The Joy of Geometry

Lecture Twelve - The Joy of Pi

Lecture Thirteen - The Joy of Trigonometry

Lecture Fourteen - The Joy of the Imaginary Number i

Lecture Fifteen - The Joy of the Number e

Lecture Sixteen - The Joy of Infinity